20 years ago, it was fun. One year there was triple miles. The aircraft were varied and interesting. Fokker F100 on one airline, Lockheed L-1011 on another. The Concorde was flying. So was the BAe 146 and 737 and A320. Back then, I was elite on multiple airlines and not just silver. Some new airports were being built, like Denver, Austin, O'Hare Terminal 1, LAX Tom Bradley International Terminal and Terminal 1, Munich, London City, etc. If there was a long layover at JFK, you could visit other terminals, even airside, like the United Terminal (9), Eastern Terminal (1), TWA Int'l (5), etc.
Now it is RJ's, no food, delays, high change fees, luggage fees, and no standby for some airlines. For a time, US Airways even tried to charge for water. A few new infrastructure projects are recent, like JFK's Airtrain and St. Louis' light rail.
I now look forward to the destination more than the journey!

I still look to fly some rare variants, like the A380 or A340-200 or 737-600, but there are few of them. I belong to many of the ff programs but have loyalty to few. My favorite domestic airlines, TWA and Northwest, are gone. Even the liveries are not as good. Continental and Alaska are the remaining good ones, maybe Hawaiian and Jet Blue.