Scheduled:
10 Apr: DCA 1515 JFK 1628 DL746
JFK 1745 BUD 0850 (11 Apr) DL91
14 Apr: BUD 1140 JFK 1525 DL90
JFK 1720 DCA 1849 DL1285
All are confirmed upgrades using SW's

Actual:
10 Apr, 1200: DL calls. 746 is cancelled ("mechanical problems") I'm rebooked on DL6224, scheduled out at 1415. Get to the airport 1300 to check in. No seat assignment available on 6224. "Get it at the gate." At the gate, no seat assignment available. "Get it at the door." At the door, no seat assignment available. "Get it on the plane." On the plane, "Sit anywhere." Fortunately, I was on the first bus and near the front. The aircraft, a Jetstream 41, has 31 seats, but 3 are "inoperable," so they can only take 28. The gate didn't know that. Last three people on the second bus return to terminal. I wonder if they had seat assignments? After the mess on the ground, we finally get to JFK about an hour late, roughly the time in my original schedule.
10 Apr, 1700: DL91 starts boarding. It's actually Malev 91, a 767ER. No First Class, just Business. Seats are only slightly more roomy than typical domestic Coach. There's a flimsy little footrest. Had to ask the FA to hang my jacket after she suggested I put it in the overhead (it IS a bit scrungy). No bar service on the ground, just a glass of orange juice about five minutes before takeoff. My reading light (3F) doesn't work - I can't turn it on. My seatmate (3E) can't turn his off. FA shrugs, "Nothing I can do." About halfway through the flight we discover that they're controlled from 3A and 3B. Fortunately, he knows the guys in those seats.
Finally, offered one cocktail before dinner. Meal is definitely substandard. Dry, tough, overcooked steak, dry, tasteless fish. Of course, it was cooked in NY (no offence, Catman; this wasn't supposed to be Ruth's Chris. I just hope we weren't eating Yaz or Eddie). Two whites and two reds (all Hungarian) on the menu. We ordered the Cabernet. "Sorry, they didn't put the Cabernet on board." Had the other red. Good.
On-time arrival. In fact, about 30 minutes early. Taxi to the Marriott takes about 25 minutes. I thought the driver said the fare was 800 and thought I was giving him 1000 (Forints). Actually, the fare should have been about 4000, and I actually gave him 10000. Bleary-eyed and slow with the mental arithmetic, I guess. Exchange rate is about $1 = 250 Forints, depending on where you make the exchange.
Marriott is a first-class hotel on the Danube. Even-numbered rooms have a river view. Recommended. Don't know what my room cost, since the meeting sponsor picked it up and I never saw the bill.

14 April: DL90 (Malev again). Immigration and Customs went quickly, although Customs was doing random checks of people LEAVING Hungary. Delta provided a pass to the Malev Lounge. Still the same tight seating. Two colleagues sitting in the back of the bus came up for a minute at one point and immediately commented: "Small seats for First Class." Maybe that's why they don't CALL it First. This time my light worked, but the seat wouldn't recline.
Still no bar service on the ground, but it was readily available in the air. The food was good. I had a turkey breast in hollandaise dish that was excellent. My seatmate this time didn't speak English, and I don't speak Hungarian, but he had a Hungarian-style meat dish that he cleaned up; so it must have been OK. Of course, THIS food was prepared in Hungary, where every meal I had was outstanding.
On-time arrival, and US Immigration and Customs went smoothly and quickly. When I was travelling regularly between the US and USSR in the 70's and 80's, the US was the hardest country in the World to get into, even for US citizens, and especially at JFK. I'm glad that seems to have changed.
DL1285: Boarded on time, then sat, and sat, and sat . . . No explanation for the delay. Finally, about 1800, passengers started boarding. About 1815, the pilot announced that we had been waiting for a delayed connecting flight. The late boarders were all speaking Russian; so I assume it was Aeroflot from Moscow - why am I not surprised they were late?
Finally arrived at DCA about an hour late. My bag had a Delta "Priority" tag, which must have meant it went on the plane first, since it sure came off last.
All in all a good trip. I just wish I could have been in Budapest a bit longer to recover from jet lag and see a bit of the city, which I last visited in 1959.