I had a awesome 29g reef tank...but you said no reef's...
I had a pair of clowns, 2 chromis, and lots of inverts...
I had more rock than I had fish...but then again I had a lot of corals packed into a 29g tank
If I was starting all over which I am ... I would definetly use sand and not crushed coral...c.c. really looked bad after the first 6 months...and after a year awful...
Get a remora protein skimmer, although the bak pak is great. The remora will allow you to upgrade later. I used the bak pak on my 29g, but know am using a remora pro on my 60g...None of this applies if you are going to use a sump...in which case I can give you no advise, since I tried it once but hated it...too much water moving around on expensive carpeting...really scared me, but people do it all the time...especially if the tank is 75g or more...
If I were you try to get another tank thats larger than the 29g...If you have one already the challenge of a tank twice the size is really cool. I am looking forward to the 60g...
Good luck