I'm more of a jamband/blues kind of guy. This was not really my genre, as all three bands got up and played their hits although the Doobies and especially Boston did jam a bit. Don Felder opened with a 30 minutes all-Eagles set, impressive mostly for the lush, beautiful harmonies. He closed with Hotel California which he wrote the music for during his 27 year stint in The Eagles.
The Doobie Brothers were next, and my favorite of the evening. You've heard the songs so many times but it doesn't matter when The Doobies deliver them with such high energy and tight musicianship. And they certainly do have a catalogue jam packed with great rock and roll tunes. They are an 8 piece lineup including saxophone.
Boston was the band that I really wasn't sure if I would like but I enjoyed their set. They did most if not all of their hits. If any band in the history of rock and roll has had their material OVERPLAYED on the radio, it would be Boston's first record. Despite personally being tired of the songs, their new lead singer is quite impressive, hitting all the notes. A sterling Don't Look Back from their second record was my favorite tune of the evening. And they proved that they could stretch their instrumental muscle with a 10 or 15 minute jam towards the end of their set.
Overall, if you're looking for spontaneous improvisation, this would not in general be your cup of tea. If you want to hear a long evening of classic rock and roll tunes which you recognize, performed well and faithful to the original version, you will have a splendid evening.