Hehe.. yeah snails can be good for larger tanks, but they are just too much of a pain sometimes to mess with.
Since you say it is a bowl, I will go ahead and suggest that you do 1 50% and 1 100% water change per week, dosing the water with the full dose for the bowl's volume of the conditioner when you do the 50%. I am assuming it's unfiltered (which is fine, since a filter is not needed, but some use it because it means less water changes).
Bettas are tropical fish, who live in warmer climates, and large amounts of waters. The waters are the rice patties, which are shallow (why width is preferred over depth with them), but are very vast and large going for miles.
Since they are picky about tank mates, they are perfect for people who want a smaller tank. They are pretty much the only fish that could live a happy life in 1+ gallons. But that isn't to say that they wouldn't like a bigger place. It's each betta's personality. Some prefer the small gallons, others really enjoy the larger tanks. Either way, it is how you take care of them, the water changes and food, heat that makes the difference in their lives more then whether they are in a gallon bowl or a 100 gallon tank.