All-season tires don't make a lot of sense for your situation. Why not have the very best (dedicated snows and summer performance tires) if you are going to have two sets of tires? Two sets of wheels is also a no-brainer IMO. Buy a used set off of this forum to save a little. As Ben said, it's way easier to swap wheels vs. mounting and dismounting tires on one wheel set. You can then sell the second set of wheels when you get rid of the car. I hope this helps.
KW Clubsport 3-way, Akrapovic Evolution, ESS Tune, StopTech Trophy, IND Euro Bumper & Black Mirror Covers, Turner Motorsports Studs/Lugs & Delrin Diff Bushings, MRF Solid Sub-Frame Bushings, RD Sport Sways, Recaro Profi-XL & Planted Seat Brackets, BMW Performance Carbon Fiber Interior Trim, BMW Edition Grills/Gills, Mode Carbon GT4 Splitter & GTS Wing, Advan TC3 (18x9.5/10.5), BBS E05 (18x10/11), G-Force Rivals (275/295)