Do we need a tour guide for Delphi and Meteora?

No need for a driver or a tour guide. It is easy enough to drive to Delphi, spend the night and see the ancient Delphi site in the morning, then head to Kastraki and visit Meteora on your own. Meteora is awesome!! Have fun!

Delphi is wonderful and your idea to spend the night is the right one. To go to he site early morning before anyone else is breathtaking and magical. Stay in Delphi.... in one of the hotels overlooking the valley. Just a note... the drive to Monevasia is long-ish
Plan on 4+ hours.... so I would plan on two nights there. Don't over do the monasteries....we did 2 and that was enough. Expect long lines snaking through the public areas and lots and lots of people. We ended up enjoying the beauty of the place over the actually monastery visits....which felt commercialized for the 1000's of visitors every day.

The 2 sites are different. For Meteora (where I have not gone), a number of friends, and others here, have said that a guide is not necessary for understanding the sites ... It is well to do "homework" in advance, and know which monasteries are open on the days you will be there.,

For Delphi, you've given the BEST advice... go in late afternoon, stay the night, then go to the site 1st thing in morning .. the huge bus crowds (8 or more) arrive about 10:30, but you'll be high up in the ruins by then (ruins go up a hill to a stadium at top). However, if it's in your budget, you'll get a LOT more from the exprience with a knowledgeable licensed guide. Georgia Hasioti, who lives IN Dellphi,, is the best-known - http://www.delphi-guide.gr/ She's in great demand, but if she's booked, ask for Her recommendation. The standard hourly rates are now €60-70 w 2 hr minimum, for a small group like yours. Very worthwhile. If you arrive late afternoon, you might check into a hotel then walk back downhill to the Museum & site entrance... you could do the museum on your own ... it will be Empty at 5 - 7 pm. (It will cost u an extra entry fee, but inquire ahed).

For best views, at a hotel, ask for rooms on DOWNhill side l... At Hotel Pan, they suggested rooms on main floor & we wondered... but when we were taken ther & walked out on balcony.... hawks were circling 100 feet Below us (!), and view was down mountain, across a valley of olive groves & out to sea.

Definitely go first thing in the morning to Delphi. We were there in early March and there were probably 12-14 buses by 11AM. Many of them were buses of school children from all of Europe and Canada with probably not an empty seat on the bus. There is a new app, put out by Hellenic Heritage (same website where you can buy tickets) https://www.hh.gr/en/digital-guide/ to Delphi. The app has downloadable guides for many sites in Greece run by Hellenic Heritage. Meteora monasteries are cash only and are €5 a person at each monastery. Some of the monasteries are very strict about women having to wear skirts or dresses. Even if the woman is wearing long pants. Most of the monasteries were quite crowded. The least crowded we went to was Monastery of the Holy Trinity. We visited two late afternoon and two the next morning. Holy Trinity was our second morning stop. Probably the least crowded because one of the harder to access. Also at the time we visited there were no tour buses visiting it. Parking for it was along the road, so much harder for buses to access.

Thanks for everyone's thoughts!

Here's an update on our June trip - love to get further feedback:
- Sun: We arrive into Athens (1st time there) by cruise ship with a day tour of Acropolis and Acropolis Museum.
- Mon: Food tour in the late morning. Quiet afternoon/evening in Athens.
- Tue - Depart for Delphi, leisurely stops. Georgia (recommended tour guide for Delphi) recommends starting tour (archeological site and museum) at 3 or 4pm since it is cooler and crowds will have thinned
- Wed - Drive back to Athens and/or go to Cape Sounion?
- Th - fly back to US

The alternative would be:
- Sun: Athens (1st time there) with a day tour of Acropolis and Acropolis Museum.
- Mon: Food tour in the late morning. Drive to Meteora, stay overnight in area.
- Tue - Tour Meteora. Stay in Meteora.
- Wed - Drive to Delphi in morning - take tour at 3pm as Georgia suggested. Drive to Athens after tour.
- Th - fly from Athens to US at noon.

Thanks in advance!

Gosh, I've never been to Delphi so I hate to say you picked the wrong one; all I can say is if I went to Greece and did not see Meteora I would be disappointed. I've been twice, and it only gets more magical. I would drive there, stay in Kastraki (recommend Doupiani House but there are others), and use Visit Meteora for a guided tour. I'm not always one for guided tours but this company was particularly excellent.

I've been to both Delphi and Meteora, and definitely I would visit Meteora.
Stay overnight. Use Visit Meteora tours to take you around. They pick up at your hotel.

My wife and I visited both last October. We arrived in Meteora in the afternoon and took the sunset tour with Visit Meteora. I highly recommend them. The coach was very comfortable and the guide shared many stories that added color to the historical facts I researched before arriving. The tour visited two monasteries and a couple other sites. It familiarized us with the area, so the next morning we easily found our way to two more monasteries before we departed. We then drove to Delphi and toured the site in the afternoon. It is fairly compact and can be seen relatively quickly. There are several excellent restaurants with magnificent views of the olive groves and ocean on the same road with the historical site. After touring the site, we picked a restaurant and watched the sun set over the ocean. It was one of the most memorable meals of our 14 day trip. These two towns can easily be done in 2-3 days.

Option 2.

But actually I would skip the food tour in Athens. Not that it’s a bad idea, but you have such a short time and I would spend it in Meteora and Delphi.

I am concerned about the timing of the Delphi site visit, early & late season the cooler comments might apply but in June? It’s still the hotter part of the day then & I don’t do much walking around at that time in June let alone on a site that’s all uphill!
Do not miss Meteora if at all possible, been 3 times, 4 or 5 nights each time at different times of the year :)

Thanks everyone for your wonderful insights and thoughts! We have decided to spend 2 days in Meteora, and forego Delphi this trip- and plan to come back to Greece another time! Hopefully during cooler weather :) too.