Two further suggestions- Neutral Milk Hotel and Elf Power. Namely, NMH's album "In the Aeroplane Over The Sea" and Elf Power's "Walking With The Beggar Boys".
We seem to be pretty similar in that regard, albeit it with different bands.
Two artists you might really enjoy if you like Mr. Oberst that much--Elliott Smith and Nick Drake. I highly reccomend them both. I had a phase with Elliott that has, over the course of different occassions, lasted about a year...Mr. Drake, about a year as well.
I listen to A LOT of different things. I have phases where I listen to one band almost exclusively. I listened to Bright Eyes for about 3 months straight. The Pixies lasted about a month and a half...Nirvana was a year.