If you are going near Tahoe, consider buying in resort. I bought my last pair in Whistler and got fantastic advice from a massive range, option to demo and a killer deal. Plus I only paid to transport them one way on the flight.
Regarding skis, it's a trade off, just like bikes, with skis anywhere from the bike equivalent of a race hardtail to a DH bike and anywhere in between.
Pick a 'genre' and underfoot width to help narrow it down, being honest about your skiing goals (don't just buy for this season - will you be 70% off piste in 1-2 years? Will a ski help you get there?)
Fatter gives more float in the powder but can be slower edge to edge.
Longer also floats better but harder to turn in.
Stiffer better at speed but harder to initiate turns so you need to be honest how aggressive and fast you are. As FD says, too stiff and hard will be too tiring, whereas too soft and floppy won't support you and will flap at speed.
I'm old school and used to teach and race. Once I got on the modern skis I went fatter and am now on 90mm underfoot (Line Prophet 90) and they are amazingly versatile from fast piste carving (wide open GS turns down Mont Vallon) and bumps, not too slow edge to edge but still have lots of float in deep pow.