This is completely unrelated, but I'm just wondering, What type of pleco are you getting? I have an odd love for them for some reason haha.
As far as excessories go a lot of people like betta logs: http://www.petsmart.com/product/inde...ductId=3956162
You should also add some caves for him to hide in, I like terracotta pots because there cheap and i just really like the way they look.
For plants you want to make sure they're arent any sharp parts on them so a lot of people reccomend silk or fabric if you dont want to do live plants. (which i cant find a good picture of, my normal LPS Doesnt sell them)
At the moment thats all I can think of, but anything else that comes to mind i'll post. Also your betta may or may not like the bubbler, it just depends on how strong it is. You can get gang valves though to control the amount of bubbles or a bobby pin works well too.
PEople also use these for their bettas to sleep on, though i;d be careful because there have been a few reports of the wire impaling fish, though many people just take out the wire: http://www.petsmart.com/product/inde...ductId=4055997