Aside: I've read the first 100-200 pages of Ulysses seemingly once every year for the last fifteen years trying to "get it" and always end up giving up. (Same for Proust and Pynchon). If you can provide any guidance about what Joyce communicates to you, please do.
(Gabriel Garcia Marquez was also in that group for a number of years/readings, but I finally got over the hump and love that style now. To the point that he may be my favorite author. I think Günter Grass was my stepping stone there.)
These books are not easy to read. They ask some work on the part of the reader. It's not entertainment. They bring much more than their story to the table, but they're way harder to read than non-fiction.
What you need is time. Lots of time. I've read the complete in search of lost time novels when I was around 15. I found it easy to read because I had nothing else to do. And I am plenty sure it changed a lot of things for me.
I've been reading the Magic Mountain and Ulysses for 10 years, unable to finish them yet, but I don't feel it's a problem. Just as you, if I try again time after time, it's probably because I know it's worth it somewhere.
Incidentally, it's not limited to old books. I had the same trouble with Quicksilver from Neal Stephenson until something cracked and I was able to read the whole baroque cycle in less than 3 months.
I highly recommend the Re:Joyce podcast by noted Irish author Frank Delaney. He deconstructs Ulysses in a very entertaining manner, 20 minutes at a time. Available at http://blog.frankdelaney.com/re-joyce/
Also, I recommend listening to the Audible version of Ulysses, which I found much easier than reading it in printed form - the language really comes alive.
I wouldn't say that I "got" Ulysses, but I made it through and enjoyed it.
That would be my recommendation — not to worry about "getting" it, and just read and enjoy the words on the page, particularly the way they sound. The prose in Ulysses is song-like, it can pull you into a trance. (Much like the _Odyssey_.) Obviously sometimes you have to look up a word, but sometimes it's better to let it go and lose yourself in the effect.
I don't know if I'd push myself through to read it nowadays, though. I am more willing to give up on a book now.
I highly recommend Pynchon (yeah, over Joyce) and recommend reading while referring to notes; there are some good websites with page-by-page annotations.
(Gabriel Garcia Marquez was also in that group for a number of years/readings, but I finally got over the hump and love that style now. To the point that he may be my favorite author. I think Günter Grass was my stepping stone there.)