Need opinions from big book enthusiasts

Im going to attempt some longer works that I have had my eye on but never invested the time because I felt the need to whittle down the pile of my unreads a bit. Ive read at least one book by all of the authors listed so Im familiar with their work and enjoyed them enough to continue on. To help me narrow it down pick three from the list that you feel I should absolutely read.

Ada or Ardor Vladimir Nabokov

Underworld Don DeLillo

Gravity's Rainbow or V Thomas Pynchon

The Glass Bead Game Hermann Hesse

Infinite Jest David Foster Wallace

I won't pick three, I'll just pick one: The Glass Bead Game. In my mind, quite possibly the most genius thing ever written. I'm glad to see that it's on your list. (As an aside, Ada is on my own TBR pile, so I'm with you there!)

Good luck!

You MUST read Ada. My favorite book of all time. Read it!!!

Not ones you named, but I can heartily recommend A Suitable Boy by Vikram Seth and War and Peace in the big book category.

I'm with 2--Hermann Hesse is always worth reading.

I agree. 'A suitable boy' is one of these books I would like not to have read yet, so that the pleasure of reading it was still mine to come.

If you are going to attempt Infinite Jest, you need infinite patience. It is a tough one to power through. I would suggest The Glass Bead Game If you are just starting on this "longer works" path.

I would avoid the Hesse like the plague. You probably won't finish it anyway, as it's one of the most boring books ever written. The general premise of the book sounds like a good idea, and it does contain some interesting ideas, but Hesse simply can't write. (perhaps it's the translation....)
I would definitely go for the Pynchon. Gravity's Rainbow is a very difficult book, but pays back in spades the effort put into it. There's not much plot per se, but rather a series of linked vignettes. It's an extended meditation on American paranoia, and a must read for anyone who is serious about filling the gaps in their reading. It's also outrageously funny most of the time. Underworld deals with many of the same themes, but DeLillo is rather insipid compared with Pynchon's bravura.
THe other two on your list I haven't read, so I can't comment on them.
If you pick GR, let me know how you get on!
happy reading

V was great, but I had a hard time getting into Gravity's Rainbow. Perhaps I should try again!

Nabokov and Foster Wallace have polar opposite styles, but I thought both were phenomenal!