searching for convenient locations in Budapest for bed and bathroom combination, total 3 nights
Check with BudapestApartmentService.com for an apartment in the center city. We stayed at Paty's Place, and it's a ground floor apartment in the best location in town. Andy Croyden is the rental manager, and he's an Englishman married to an Hungarian. Nice guy.
If you are going in June through September, air conditioning is helpful; but not as common as you would think. Ask.
I think the most convenient location for a tourist is District VI. That would be one block above Andrassy ut to Kiraly utca on the otherside of Andrassy ut. From the lower end of Andrassy ut to a block or two above the Oktogon. Plenty of evening strolling and well connected to all of the sights in town.