Hi Fred,
yes, the aspen works just fine for the framing material, i'm using tulip poplar for my board and baton siding, not sure if aspen would work or not....one thing I found that helped was when I cut my framing material. I cut evrything and inch over size for width...my 2X6 studs were actually cut at 6 1/2 inches, then stacked and stickered and allowed to dray for about 4 months. When I was ready to start my construction I loaded them back on the mill and trimmed them down to the normal 5 1/2 inch width. was a little extra work, but sure made the boards a lot nicer to frame with. I did the same thing with my joists, I put them with the crowns up, trimmed that side and marked it with a carpenters pencil, then trimmed the other side. when I rolled out my joists I looked for my pencil marks, ensuring I got the crown up. good luck on your project...It is a very nice feeling to be able to look at the shop and know we cut the lumber ourselves, in Ohio we still don't have a bunch of permits to pull so I got by the aspen no problem.
God bless,
Steve