I haven't fished down around Albany,but I have caught several small mouth up at the rest area at Jefferson on I-5. If you go, go to the southbound side and you will see a small parking lot right on the river. Good luck, that is the same place I caught my one and only steel. Be safe.
Usually there are more smallmouth in the actual river than there is largemouth. In side channels and sloughs there are definitely some nice largemouth. There is great smallie fishing around Bryant Park where the Calapooia flows into the Willamette. This time of year I would focus on very slow moving areas where the water might be warmer, forcing bass towards the spawning cycle.
This time of year I haven't caught much around Albany in the Willamette. In the next month or so it gets hot between the bridges in downtown to Bowman Park. Fishing Rebels near the bank you should get quite a few smallies in that area. If you want more action though try drifting the Calapooia between 34 and Bryant Park in May.
I have caught both large and small between Peroia and Corvallis. I have caught a lot more smallies than bigguns. The small mouth seem to love spinners near the rocky outcroppings of the confluence of the sloughs and river. I have seen some nice fish pulled, both large and small with a white grub on a jig head. Just depends on where you fish and cast like Zen said.