Budapest only 1/2 day then flight

There are a number of companies and they are all pretty much the same. We’ve done two of these with two different companies, one was Legenda, the other I just don’t remember.

http://www.budapestdanubecruise.com/
http://www.budapestrivercruises.com/
http://legenda.hu/en
I am going to suggest that with such little time you might want to do something else. Most of the lights can be seen from river embankment. This for instance had to have been taken from the Pest embankment about 30 feet from a nice café. https://upload.wikimedia.org/wikipedia/commons/6/69/Buda_Castle_by_night_2.jpg

If I knew where you were staying I could do better, but in general you might want to get a 24 Travel Card at one of the metro stations and then do the trams. They make excellent HOHO busses with much more character and charm.

In general you would take the 47/49 tram from Deak Ferenc ter past the Great Synagogue to Market Hall.

Go up to the second floor and look at the Hungarian trinkets, then the #2 Tram along the Danube Embankment to the Chain Bridge.

Then walk across the bridge and take the funicular to the Buda Castle. Spend an hour, then back down.

Now the #19/41 Tram north to Margaret Island Bridge. Get off at Batthyány tér if you just want to stand and look at the Parliament. Otherwise on to the Margaret Island Bridge where you board the #4/6 Tram back across the Danube.

The first stop on the Pest side of the river and a very short walk will take you to the #2 Tram that circles the Parliament Building.

Get off after going past the Parliament and then see the magnificent government buildings, banks and embassies as you walk through Szabadság tér to the Cathedral.

From the Cathedral to the end of Andrassy ut and walk up Andrassy ut to the Opera House, now board the M1 metro to Hero’s Square.

Its dinner time so walk over to Paprika Vendéglő (have a reservation).

Now take the M1 metro back down Andrassy ut to Vörösmarty tér, then a short walk to the embankment to see the lights, have a glass of wine in one of the restaurants along the embankment or on Vaci utca (the tourist street one block in from the river). Maybe go to Fat Mo's.

Depends how late you wish to be out but given you're starting after 2100 I'd agree that you could get a lot of flavor of the river cruise by walking a short section of the embankment or lingering on one of the bridges. Then you could spend the time saved by enjoying a bit more of the vibrant nightlife. The cruise would be more relaxing although you will have been sitting 2h during the opera. I enjoyed the view from both sides of the river near Parliament by hopping on and off the subway - there's a stop conveniently located on each bank. I liked the view of Pest (from Buda side) more, but there's somewhat less diversions on the Buda side as you walk in terms of cafés or bars at which to stop.

Oh, heck, I read Opera like a site to see and missed "out @ 2100" ; so you are seeing a performance. So my idea ends at Hero's Square, or one stop sooner, then you go get ready for the show. I don't think there is a boat that late so make reservations at Callas Cafe, sit outside and people watch on Andrassy ut. Then a night cap on the embankment via the M1 metro in front of the Opera/Callas Cafe.

Okay, here is what I would really do. I would to the tour I described, but I would cut it short and change for the opera and go to Lugas http://lugas-etterem.com/ for dinner at 6pm. Personally I would order the Toltott Kaposzta and a beer. Then, after dinner, I would walk up Andrassy ut to the Opera House. After the Opera performance I would walk across Andrassy ut and up along the left side of the Drechsler Palace (that large building across the street from the Opera that at one time or another was the Ballet Academy and a retirement home for railroad workers and hopefully someday a 5 star hotel). At the end of the street there is a slight jog to the right, then the street continues. On the right there is a yellow apartment block. Wave hello and if I am there I will wave back. Now continue to the next intersection and on the left is Kadarka Wine Bar http://kadarkawinebar.com/ . This is where I would spend the rest of the evening. Then I would walk back down Kiraly utca to the river embankment where I am betting you are staying……. And where you can see the lights. Now you have seen some of real Hungary, eaten some real Hungarian food, participated in a real Hungarian opera tradition and drank Hungarian wine in a real Hungarian wine bar.