WiFi drops in Yosemite

The wife and I both installed Yosemite. It's slow, wife's WiFi drops off every 15-30 seconds. Turned off BlueTooth and it's some better. Genius Bar was sympathetic. When you forward or start composing a new email there's no option for your contacts list. Using for business this is a complete bust. JP

What are the basic specs of both your Macs?

Yosemite nightmare

Main-Framer here.....
Both are 13" MacBook Pros - mine mid 2009 (2.53 GHz Intel Core 2 Duo+4 GB 1067 MHz DDR3) , wife's is mid 2012 (2.5 GHz Intel I5+4 GB 1600 MHz DDR3).

The WiFi dropping is an issue that has cropped up for some folks, but there doesn't seem to be any one common fix. I read on one website that there are 40 or so things to try, but none of them works consistently for everyone. At this point, it's an unknown. Can you use wired connections just to get back into production?

The contacts thing, assuming it's in Mail, works for me by just typing in a few letters of the email addressee or distribution list name and it opens a short list of suggestions from which I can pick. Is that NOT working for you?

WiFi dropping was my wife's problem. We've pretty much got that licked now.
As for the Mail - Yes, I can type a few letters and some suggestions will show up. With as much mail as I do that's a terribly slow way to go in spite of distribution lists. I'm checking into Outlook for Mac.