With a 38 gallon, I would vote for something like the community tank you've listed here. I'd start with a set size--say 4"--and not exceed that length. That would let a pair of GBRs and a pair of Angels be your showcase fish, and that would be a brilliant show.
I'd probably start with the three platties (well, after your mollies and your cory). Then, you could up the cories and the mollies.
Then, I'd do the harlequins or some other small schooler.
Here's where you might not like my advice. Given that you'd have 3 each of mollies, platties, and cories (and you might consider strongly going to 5-6 total cories), you'd have 9-12 fish, and those live bearers are bigger loads. Let's consider the angels/GBRs 1/3 of your tank's load. Let's take the mollies/platties/cories as another 1/3 (really larger, but you get my drift). We'd have something like 7-10" of fish left. I'd try going with harlequings/small schooler (even neons) here. With something smaller like a neon, you'd get 10 for sure.
At the slight risk of overstocking, I'd risk a pleco here. You'd have the physical space, and you would just need to take your time to maintain the tank. I'm nixing from your list, in other words, the badis, killifish, shark, and swordtails. If you do lose a fish or so, you could look at the other options, and you can keep your ear to the ground here for interesting fish not needing conspecific companionship as potential replacements.
I'm not sure I'd start into the bigger cichlids now--these are fish that could well survive into your university years, and you're getting a beautiful new tank. I myself went with the smaller fish so that my new tank (21g) wouldn't seem too small, too fast. Those shell dweller tanks that folks post here are rather beautiful--those might be your best cichlid option if you do end up not getting angels and rams.