Don't get Clown Loaches. Like the Common Pleco, they'll grow large and need a minimum of 55gals (when they're young) and when they mature, they'll need over 100gals. I believe all the other Botia loaches stay small and are a good choice.
Bristlenose Plecos are popular, and it's fascinating to watch them grow, wait and see if they're males or females (if it's a male, the development of the bristles is fascinating). Best get them some driftwood, though. Same with any other Pleco. I also have a Rubbernose Pleco (also called a Bulldog Pleco) and while the big fat head of him freaks me out, he's pretty cool to watch. They love rocks, though, and mine was a shy little spooky guy until I got him a big rock. Now he's a feisty little bully who chases off the Bristlenoses when they dare get too close to him.
Ottos are busy little guys, great algae eaters, but they're sensitive and probably not the best choice for a new tank.
For loaches, I've fallen in love with the YoYo Loach (also called Pakistani Loach). Very active, curious, violent to snails (judging by what I saw one of them do mere minutes after releasing him into my tank that had pest snails), out and about day and night. They get along with everyone, no fighting or pestering. They do best in groups, though, and as a group, it may overstock a 30gal (they can get up to 6 inches, I believe).
Have you thought about African Dwarf Frogs? (not to be confused with African Clawed Frogs). Cute little guys, though it would be best for them to be in a tank that's no higher than 20 inches. Otherwise they'll have to work a little more to reach the surface when they need air. Otherwise they spend all their time at the bottom of the tank being cute. They need a little more special feeding care, though, especially if they're in a tank with other greedy fish. They don't have the greatest eyesight, and they have a reputation for being helpless, so you should get a turkey baster and deliver food literally to their mouths, so that they have a chance for some nutrition. Otherwise, any food that you put into the tank will have been devoured before even one flake or pellet reaches the gravel/sand.
Whatever you consider for your tank, take into considering the substrate you have. Gravel isn't great for the frogs, as they have been known to drown when a foot gets caught under a rock. But they can't have fine sand either, as they can ingest it when they hoover in their food and it can cause problems. Likewise, the bottom feeder fish with barbels (like Cories and Loaches) prefer sand so that the barbels don't get worn down. Some fish have sensitive bellies that don't go well with sharp gravel/sand, and some fish love to sift through fine sand (I know I read once that Kuhlis like to sift through mulm, or something like that). My two Kuhlis do love going through the sand to find leftover food, and I swear they like going through the spots of poop buildup (ew). I'll also watch them dig a hole in the sand as the sand particles are shooting out their gills (or whatever is going on, lol)
You can also take a look at female Bettas, start up a sorority of them.
