Budapest for 3 days

So as I understand it now you will have three full days in Budapest
Bring a small stone from home. About the size of a quarter will do. But a pretty one.
If you were staying somewhere along the M1 Corridor possibly near the Opera House then this day I would do this:

DAY ONE

1. Eat Breakfast
2. Opera House (outside). Then the Opera Metro Station to get metro tickets (book of 10)
3. Walk up Andrassy ut to the House of Terror (get past the name, excellent museum) 1.5 hours
4. Andrassy ut and hop on and off the M1 metro so you can walk some of this wonderful street until you reach Hero’s Square at the end of Andrassy ut and then on to Vajahunyad Castle (you know it’s a 19th century reproduction, right? Still very fascinating). Then the City Park, bath house, etc. (Varosliget) 2 to 3 hours total time.
5. Its noon or slightly thereafter. Since you are where you are I suggest you go to Paprika for lunch http://www.paprikavendeglo.hu/
6. Walk back the M1 at Hero’s square and take it back down Andrassy ut to the very last stop. Walk a little further and you are at the Danube Embankment. This is the view you came to Budapest for.
7. Walk to the Chain Bridge, cross on foot, take the funicular up to Buda.
   
8. Get your guide book and tour the Buda Castle District.
9. About 5pm you want to be heading down the funicular. At the bottom see the yellow trams. You want face the river and then take the tram going from left to right.
   
10. At the second stop you are at the Famous Gellert Hotel; having served the likes of Heinrich Himmler and Oscar Schindler.
    
11. If its early go in the lobby and look around. Also famous for its bath house, one of the finest in Budapest.
12. Look for the 47/49 tram that crosses the river and hop on. The first stop is the Great Market Hall on the right and Vaci utca on the left. Sorry, not today.
13. Go up two more stops (Astoria) and get off and walk in the direction you were traveling on the tram. On the right is the Dohany utca Synagogue (Central or Great Synagogue). Not today. I am getting you back to the room to get cleaned up for dinner.
14. A couple of blocks after the synagogue look for Dobb utca on your right. This takes you into the WWII Jewish Deportation Ghetto.
15. Up Dobb utca until you see Spinoza’s Café on the right. Here on Friday night there is a typical Hungarian Jewish meal and a Klezmer concert. Worth doing if you are there on a Friday night. Across the street from Spinoza’s is the entrance to the Gozsdu Udvar (Courtyard).
16. Go through the courtyard (shopping, bars, restaurants, etc) and exit at the other end on Kiraly utca.
    
17. Right on Kiraly utca and then the second left (Vasvari Pal utca). Here you find my favorite wine bar (Kadarka), a great hidden Synagogue and a yellow apartment building (wave as you pass and I might wave back). Follow the street to the end, make a slight jog and continue till you see the Opera House.
    
18. Head for Macesz Huszár “Jewish Bistro” http://maceszhuszar.hu/ about 15 minutes before the time you made reservations (7 to 7:30 is typical for dinner). You will recognize the path back into the old Jewish Ghetto. Pretty authentic Jewish/Hungarian fare at good prices and decent service. Nice folks too. http://maceszhuszar.hu/eng.html
19. Head back to the Opera House by way of Vasvari Pal utca where on the corner you will find Kadarka’s Wine Bar for a glass of one of Hungary’s best vintages before the 5 minute walk back to the Opera and presumably somewhere near your accommodations.
20. Feel free to wander anywhere. Budapest is incredibly safe, day and night.

DAY TWO

1. Buy some flowers from one of the Andrassy ut sidewalk vendors. Take them with you.
   
2. Take the metro from the Opera (or walk) to the end of Andrassy ut and then the 47/49 tram one stop then walk back a little and visit the Dohany utca Synagogue (“Central Synagogue”). Take the tour. Worth it. You will see where to leave the stone you brought from home.
3. Back on the same tram in the same direction a couple more stops and you will find the Great Market Hall. My guess is that if you are having a good time that it is noon. Eat lunch in the market hall top floor. This is primitive, I think good (DAVID!) local fare sold primarily to locals. But its not fancy.
4. Now get on the Number 2 Tram to the Chain Bridge. This is a great tram ride. Sit on the river side of the tram. The stop is just before the bridge. Get off and walk under the bridge.
5. Walk the embankment to the Shoe Memorial. Leave the flowers your brought.
6. Walk back to the Chain Bridge and back under. That beautiful building at the head of the bridge is the Four Seasons Hotel. When facing the hotel you assignment is to work your way over to the left hand side and make your way up the pedestrian road to the Basilica.
   
7. About half way to the basilica you will see a Music themed shop. I like it. At the basilica to the right are some of the better quality souvenir stores in town where you can buy the amazing Gomboc among other uniquely Hungarian “stuff”.
8. Tour the basilica and climb to the top (or take the elevator if you are a light weight) to the top for the view and to see how domes are constructed. Pretty interesting.
   Okay, if you are in Budapest after the 15th of September and if you brought something equivalent to Business apparel then I say go to the Opera or the Operett, then have dinner at Callas Café next to the Opera house. If that isn’t an option then let me know if you want cheap or memorable and if you want tourist or local (nothing wrong with tourist, you are on vacation and I will send you to a good one) and I will come up with some suggestions for dinner. The problem with Budapest is that there is just too much good food at good prices.
   
9. After dinner (if you dont go to the show) walk up Andrassy ut until you get to a magnificent building with an arch on the façade at no. 39 Andrassy ut. Up the escalator to one of Budapest’s grandest coffee shops to relax before heading home.

DAY THREE

Head for the Parliament. From the opera you have two choices. Either a 20 minute walk or shorten it by taking the M1 to Deak Ferenc ter and then transferring to the M2 for one stop. Still going to take you 20 minutes but less effort. http://www.budapest-parliament.com/visits.php

Okay its early. This is a day to do a speciality tour. Something that really interests you.
Jewish Budapest walking tour
WWII memorials and monuments
Soviet Occupation memorials and monuments
Antique shops in endless connected basements
Fantastice 19th century cemetery monuments in an incredible park
The Dispair of District VIII
River ride
Quick trip to Szentendre artist village
Quick trip to Godollo Palace
Vaci utca shopping (personal yuck!)
One of a half dozen magnificent 19th century bath houses
Margaret Island
More magnificent buildings
Eiffel’s pre-tower train station
Buda Hills
Buda Hills rail road run by children
Ski lift through the Buda hills
Drive a Russian Front Line Tank
Drive a Trabant

Dinner. When I get your input I will give you some ideas. This is a town where fantastic food in fantastic settings is at pretty reasonable prices. Take advantage of that if you can.
GENERAL
Once I know where you are staying I can give you some breakfast ideas.
Everything I suggest is subject to what day of the week you are in town.

I didn't see any swimming baths on your list. Those are a very fun, relaxing cultural experience.

Right in the middle of the list: "One of a half dozen magnificent 19th century bath houses" The ones that are more about recreation than wellness translate to "Beaches" (odd). But they depart somewhat from the cultural icon of a Bath House. Still fun though

http://www.spasbudapest.com/

I'm not the original poster but I'm going to adopt your suggestions for my 3 1/2 day visit, particularly excited to hear some klezmer music and check out antique shops for a unique souvenir.

Here is the link for Spinoza's that has the meal and the klezmer concert on Friday night http://www.spinozacafe.hu/index_Eng.html

This Klezmer Band is very exceptional if you can catch one of their concerts::

http://www.budapestklezmer.hu/en/about-us?mini=koncertek%2F2014-06

The first band is very good, the meal is good and the atmosphere is good. The second band is amazing if you can be there for one of their concerts. another option is a musical called the Wedding Dance at the Operett theater. All of the music is done by the second band above. Good show to and I love the operetta theater.