Dune is my favorite sci-fi book.

I have no idea what books there could possibly be that are like soase.  never heard of any.

If you like fan fiction, look up Distant Stars Lore.  Its the biggest (and as far as I can tell, only) soase fanfiction.  Its really big and the writers are actually quite good.  The story of tier is probably my favorite, and its about the advent.  Stant and the core Distant Stars team are also really fun to read.

I am very impressed with the suggestions made.  I thought I was a lone voice in the wilderness! 

But 3 I did not see (and I only skimmed the comments, so please forgive me if I overlooked the recommendations) are:

Fred Saberehagen - Berserker Series

Philip Jose Farmer - Riverworld Series

Theodore Sturgeon (he is mostly short stories, but excellent).

I noticed others giving you the Asimov series, Clarke, Herbert, Heinlein etc.  What I would suggest is you pick one (all are excellent as well as the ones I gave) and read all the books in the series.  That advice is probably not needed since any of them will hook you and you will WANT to read them all.  You have the distinct pleasure of not having to wait for the next book to come out and read them at your own pace.  Many of us read them as they were being written, so had to wait months (sometimes years) for the next installment.