Very cool Jeff!
The indoor range and rental gun set up is a lot of fun for the shooter, and can help boost your handgun sales when people try a gun that they just "have to have". I've enjoyed many hours shooting at a couple of the local indoor ranges over the years.
Make sure you have the proper waivers and lots of insurance.
I'm sure you've researched things thoroughly, and this is by no means an attempt to scare you into not going forward. I just want to make sure you CYA before opening the doors to the public.
Here's a couple of links regarding some tragic local events at indoor ranges over the last 10-15 years. I do unfortunately remember each of the Seattle area stories being in the news.
http://www.seattlepi.com/local/shot083.shtml
http://www.p45.net/boards/showthread.php?t=11935
If you haven't done so, I would take the time to call some of the owners of indoor ranges and ask for any insight they can offer to keep YOU safe legally and physically.
Best of luck with your new business!