I'm pretty fortunate in that on most of my commutes i don't have to lock my "bike de jour" at all. The local Wendy's manager lets me bring it inside and i park it against the back row of tables right across from the bench seat i'll be eating at. So it's in my view at all times.
At the local McDonalds, i do use a basic cable lock but keep the bike in view though a window, and once my food is ready i sit in front of the window a few feet from the bike. This is only a few days a month, as i much prefer Wendy's baked potato and Asiago grilled chicken sandwich,....so they see me almost every day. (sometimes 2x a day but i;ll get a cod fish sandwich on the 2nd trip:-)
I shop a few times a week for groceries at the local Price Chopper supermarket, and bring the bike right in with me and walk it around carrying a hand cart. Once i check out, i transfer the groceries into my shoulder bag and off i go.
I guess what i'm saying is the BEST way to keep your bike is to have it view at all times, or within easy reach and visually accessable.
.....so far i've never had a bike lifted or even attempted :-)