Looking for some Lisbon guidance

Sintra is going to be busy, no matter when you go! But May or June will be very busy. To me, the palaces, etc. are the only reason to go to Sintra - but there are others that like the town itself. I would say to go on the Friday and attempt to get there when the first Palace you want to visit opens. Depending on your speed, you can likely see 2-3 comfortably. Study the bus transportation before you go. There is a small bus that visits all the main palaces and the big bus just goes up to Pena with a stop at the Moorish castle ruins. You can stop once on the way up but not on the way down. Walking to Quinta da Regaleira from town is easy and this is my favorite place (so far). The grounds, not the house, are the draw, and very much worth a visit. There is very good information on all the palaces to help you decide which 2-3 to visit.
Foe other small towns to visit - Obidos and Tomar come to mind if you want quaint but neither are on the coast. Evora is also lovely and doable as a day trip. Cascais (where I live) is the easiest to get to and is a lovely place to spend a day. There is a walkway along the coast from town overlooking cliffs, with places to have lunch, sangria, or whatever overlooking the sea. Cascais is a fishing village but is pretty upscale and I don't know that I would call it quaint.
Regarding a hotel or apartment, there are many inexpensive vacation rentals in Lisbon but you might want to look fairly soon. The tourist traffic in Lisbon exploded last summer, so earlier is better. I would suggest the Chiado or Rossio áreas.

I lived just out of Lisbon fro a year about 5yrs ago.

Sinatra is a great! I strongly recommend staying the night not so mischievous due to the crowds but due to so much to see. There is the Pena palace, the mores castle (brilliant first thing when it's all misty) there is another castle in the centre of town but I can't remember it's name BUT go to Quinta de Regalera. (Hope it's spelt vaugly right)
Its gothic, it's amazing it has a free masons initiation well, I could go on and on, but it's fascinating and like nothing you have ever seen. That in it's self will take up most of your day.
From Lisbon take the train out towards Cascais, get off at the discoverer monument, visit that and the st Joel (??) cathedral, nice lunch places there.
Then hop back on the train and go to Estril get off and once you have finished there walk along the board walk to the last town Cascais which is also beautiful, lots of places to have dinner there then after a few beers you can catch the train back to Lisbon. All too easy.
While in Lisbon make sure you visit and go up the elevator which was designed by same guy who did the Eiffel Tower. Dinner up in the castle on the hill is Devine, view is spectacular.
Loved my stay in Portugal and I don't speak anything other than English so while I did get served some strange dinners it was a great experience and will give o back one day. Enjoy!

My wife and I had a wonderful 8 days in Lisbon last October. I loved every minute. We plan a 2 week trip to Porto this coming October. I had a Skype based tutor to give me the basics of Portuguese and was glad I made the effort despite the fact that many there learn English in school.

1. We were very disappointed with our day trip to Sintra. It was the only time we felt we were "tourists". Long lines, overpriced food.
   
   Maybe it was just the day we went

2. As a sailor, I thoroughly enjoyed the day trip to Belem. We took a taxi as, other than the Metro, we found public transportation (especially the buses) crowded and infrequent.

3. We stayed in the area around Principe Real (Jardim Fialho de Almeida). Quiet at night and a real little community with butchers, a fishmonger and great restaurants. We went through AirBnB and found great accommodations. The hosts were Diago and Cousins.

For a hotel in Lisbon, check out Browns Downtown Hotel. Clean, convenient to all sites in the ETB guidebook. Very cool large rooms. I don't know if it's included in your tour but visit the Gulbenkian Museum. It's a gem!

Many thanks for these speedy comments and recommendations, as I am during these hours and days finalizing my flights, reservations, etc. Based on the mostly very positive comments on Sintra, I have extended my already long trip schedule to arrive in Portugal one day earlier, and have made my flight arrangements to do that. With the extra day, my thinking was that maybe I would go directly from LIS to Sintra, spending my first relaxing evening, night and the next day there, moving on to Lisbon the next late afternoon. That would give me a chance to enjoy the quieter times and a full weekday in Sintra. I love the misty times. Does that sound like a good idea? Any thoughts on the best way to go directly from LIS to Sintra, just one person and one bag, I understand a taxi would be about 50 euros. Also, any recommendations for a modest place to spend just one night in Sintra? Obrigado de novo.

Sintra is touristy, but lots of fun. The earlier posts give good advice.
I don't know where the RS tour goes in Lisbon. There are interesting neighborhoods to explore, and you may find plenty of interesting things to do without leaving the center of the city. Having said that, Cascais is a nice day or half day trip out of central Lisbon. Cascais is pretty, easy and more relaxed than central Lisbon.

The train from Lisboa- Rossio to Sintra costs €2.20 and runs every 20-30 minutes. See http://www.cp.pt
The Aerobus #1 cost €3.50 and goes from the airport to Rossio. See https://www.aerobus.pt

Sintra is absolutely magical and deserves two nights (one full day). We did not find it crowded at all when we visited in late September 2008, but it might be different now. Cascais is a great stop too, but we found hotels were really expensive and dumpy for the inflated prices (so better as a day trip). But again, might be different now. Obidos, Nazare, Tomar, Evora, all well worth a visit. If I had to pick one of those four it would be Obidos. I don't recall which place we stayed in Lisbon but it was well located near the Elevador de Santa Justa. The location was just perfect!

Before you give up on the Lisboa Plaza email your request telling them you are with the RS tour and requesting a reservation. We just booked two rooms way less than the rack rate you quoted in your post.

Thanks to all of you who offered guidance here, and also through PMs. I have considered all your ideas and recommendations in developing my plan for these pre-tour days in the Lisbon area. For you, and for anyone who may have similar concerns and read this later on, here is my plan, already booked:
1. Spend my first two nights, thus a full day plus parts, in Sintra, at a lovely B & B called Chalet Saudade, a deluxe double room at 83 euros per night.
2. Spend my next three nights in Lisbon at another fine B & B called Casa C'Alma, a large deluxe suite at 105 euros per night.
3. Then move to the Lisboa Plaza Hotel for the beginning of the RS Tour. I understand the the Lisboa Plaza is available to RS travelers at rates well below the rack and booking.com rates, but those are still well above what I am paying in these nice B & Bs, both noted for their hospitality and staff.
When I look for lodging, I always look for modest rates, great locations and ambiance when possible, and then often go for a more spacious room, even if a little extra. If it's just for 1 night before or after an RS Tour, I usually stay at the tour hotel, even if a little more, just to avoid the time involved in moving.
All this should give me some relaxation in Sintra after my long flight, and a chance to explore both Sintra and Lisbon at leisure, and maybe even take a day trip from Lisbon to Cascais or elsewhere in the area.
Most of the other spots mentioned by some of you are already points on the RS Tour, except for Tomar.
The RS Tour ends with 1 night in the Douro Valley and 2 nights in Porto. I have then booked a lovely apartment for 4 nights in Porto, and hope to spend some time exploring the very north of Portugal, maybe across the border to Santiago de Compostela in Spain.
I do have a US Passport, so hopefully our government will allow be back home at the end of my trip. LOL and (:->( )))

Thanks to Rick's generous contribution to the ACLU, you should be able to come again. ;>)

Larry, if you do head up to Santiago de Compostela, there are some interesting places to stop along the way should you have some extra time. The small Spanish border town of Tuy is interesting, but the international bus probably doesn't stop there. The cathedral in Tuy has an English audio guide.

Pontevedra is sunnier than SdeC (could be good or bad) and its medieval district--unfortunately not near the bus and train stations--is worth wandering around. If we can trust Rome2Rio.com, Pontevedra's where you might switch from bus to train on your way north. Vigo can and should be skipped.

Must admit I had seen a listing of a day tour that goes to Santiago de Campostela and visits Valenca do Minho in Portugal on the return. Not sure I would take the trip on my own, with various other towns and connections on the way, or rent a car to drive by myself, although I suppose that is a possibility.

We went on the RS Portugal Tour last September. We loved it. The cork/olive oil/wine farm was the highlight for me but being in the Douro Valley during wine harvest and squishing the grapes with our feet was also memorable.

We started with 2 nights at Chalet Saudade (https://www.tripadvisor.com/Hotel_Review-g189164-d5984709-Reviews-Chalet_Saudade_Vintage_Guest_House-Sintra_Sintra_Municipality_Lisbon_District_Central_.html). If you look at my TripAdvisor review history you'll see several other reviews I wrote on Sintra and other stops on the tour. Sintra was unpleasantly packed during the day but lovely in the morning and evening. We got up to the palace on the first bus, visited it, walked over to the Castle of the Moors and then walked down to town via the Vila Sassetti trail which was really nice. The person at the front desk at the chalet told us about the trail.

While we liked Lisbon it was our least favorite of the places we visited on the tour and we thought we had enough time there. Porto was a more interesting city.

Almost everyone speaks English and speaks it well. It isn't like in other countries where only the young people speak English.

Have fun!