The 7 gal mini bow is a nice tank, gave it to a friend of mine for X-mas one year.
If you want to grow plants, you will need to get the proper lights for it. The one strip light may not be enough wattage for plants. I recently bought myself the 2.5 mini bow from Walmart which has the incadecent bulb. Instead of using the bulb the supply, i went out and got the mini power compact that you can screw in. I have crypts in the tank right now and they seem to be doing fine. But I have the tank for only a few short weeks.
It might be cheaper to get a 10 gallon and start with that. In the long run a 10 gallon can be a cheaper setup for the cost of that 7 gallon mini bow. I have now seen 15 gallon talls going for $24 (us) at petsmart. So there are many options you can try here which are far cheaper.

But if you go with fish, If you do not go with the betta, guppies would be fine or a paradise fish. I have kept Bettas with guppies but only in large tanks. There are many other types of fish that would be good to keep in here. A small school of Danios would make a nice selection here.
As for small tanks, i use them all the time. I currently house many live bearers in these tanks.
In my 15 gallon i house, Endlers with Merry Widows.
I currently use 5 gallons for housing Gambusia (mosquito fish) and Pygmy Killie Fish (Leptolucania ommata).
In my 2.5 at home, i keep Least Killifish (Heterandria formosa). Which i think would be the perfect fish for a tank like that. You would be able to keep about 15 - 20 fish in that tank easily.
jim