"Easy to manage" is soooo subjective! lol
In my personal opinion, a 30 gallon tank wouldn't be that much more difficult to manage than a 10 gallon tank. Its a little bigger, a little more, but that doesn't mean it is necessarily harder.
My personal preference too is a tank that is longer than it is tall. I really don't care for tall tanks, which so many seem to be. The longer tanks offer more surface area for oxygen exchange, and also gives more area for fish to swim (like birds, many fish are horizontal moving creatures, not so much vertical, they WILL move vertical, but many prefer horizontal. The advantage to taller tanks is that you can keep different "levels" of fish (top-water fish stay at the top, mid-water fish stay in the middle, and bottom-dwellers stay at the bottom, more variety, but also easier to over stock).
I currently have an aquarium with fish and plants. I started out the cycling with plants. The plants help remove some of the harmful chemicals (such as nitrogenous wastes), so can help speed up the cycling process and keep the cycle cleaner. My fish are a little "neglected" right now, they are housed at my dad's house while I am trying to get through the escrow process for the house I'm buying and get moved in. Once that's over I'll take my fish back. Despite that, they are VERY happy fish.... I have a pair of platies, a guppy, two botias, and an algae eater. Let's put it this way - after years of keeping platies, I've NEVER had babies. Always had babies with guppies and mollies, but never with the platies. Well... now, after my fish have been "neglected" a few months, they won't stop having babies! There are over a dozen babies in there now, and I don't mean newborn fry that are going to get eaten, I mean babies that are several months old and doing quite well, with new babies popping up every few weeks. I blame the plants... hehe
(Once I do get to moving the, I'm going to set up a second tank, move the adults first, make sure all the babies are big enough to actually catch, then move them over and break down the old tank. As it is now, I'm afraid the babies will hide in the gravel and get lost/injured/killed if I try to move everyone at once.)
I personally like livebearers. They are hardy, and relatively easy to care for. They are also very peaceful, and get along well with each other and other fish. I don't care for cichlids or barbs and many tetras (too aggressive), I do like the loaches but they get big (my botias are staying small). I also have a soft spot for goldfish and koi, but they shouldn't be kept with tropicals (prefer colder water) and really do best in a pond than a tank (my dad's aquarium has a feeder goldfish I "saved", started out at 1 inch and is now nearly 10 inches long, soon as I get moved I'm going to get a "bucket pond" and take him too).