I'll just add my $0.02 as to what I do...
4-Stroke
Sta-Bil and Marvel's Mystery Oil in every new gas purchase. According to the directions on their bottles. When nearing the end of the season, I buy a new jug of gas and top off all the tanks with that. Let them sit and fire 'em up when I need them in the spring. Been working well, and the 2008 model Briggs I have has no Ethanol related problems.
For the snow blower, that gets drained, run dry and the carb bowl dropped. A liberal application of WD-40 on the carb and in the carb. I do that because if the SB sees 5 hours a season that's a lot and I imagine the fuel gets quite watery as it does kick up snow and that melts all over the engine and tank..
2-stroke
I run Stihl UP oil in the 2 stroke gas. When I think the season is winding down I switch to a can of Tru-Fuel and run that until I'm done. That was a tip from the Stihl dealer as the TruFuel won't gum up the tiny passages and will not kill the rubber diaphragms in the carbs When done, they go away for the season and new gas gets bought in the spring.
This seems to work for me. I'm mainly a Briggs/Tecumseh/Stihl guy but have a Chonda on a generator that gets the same treatment and runs well too. The gen gets run for 30-60 minutes every month with a 50-75% load on it. That keeps that guy purring right along.