Green lily hit it all very well
To aid in Cecil's advise.
For a 63g I think you would find African (like you stated) more rewarding and better suited for a 63.
There are many different types of fish to look at.
Tanganyikans, really cool fish, unique, not many all Tang tanks out there.
An all Tropheus tank would be sweet.
There are also some really cool Tang shell dwellers, they are generally smaller, so you could have a massive stock. You can also mix tons of varieties of Tangs, the difficulty in this comes primarily from dietary needs which can vary greatly. Most would not mix a Tropheus breed with a Calvus breed for example.
Malawi tank, (my suggestion) includes larger Haplochrimis/Protomelus species. Usually larger fish (5/9") unique and very colorful. Aulonocara, (peacocks) are very beautiful, and have amazing colors and patterns. They tend to be the less aggressive species in Malawi, an all male peacock tank is amazing. (There's tons of other species that fit in with these two. (Nimbochromis, Otopharanx, lethrinops, many others)
Another is Mbuna (Rock dwellers) these are known as the aggressive African fish, (though not all) they include many genus, most commonly Psuedotropheus, cynotilapia, labidochromis, and many others.
You can also do mixes of Haps, Mbuna, and peacocks, but this takes some special planning to get species that will co habitats together, to keep it simpler I would just focus on one type.
Victorians, these fish are brightly colored, and very stunning Pundamilia Nyererie is one of my favorites, there is also a large group of Haplochromis Victorians
Common odd balls for a Cichlid tank are cuckoo cats (group of 3 or so) and threadfin cats.
There are SO MANY Africans it can be hard to choose from.
My advice is to plan, plan, plan. Check what is available to you, either in your area, classifieds, or online. And research the fish your interested in thoroughly before buying. You can do an all male tank (females Africans typically do not show any color) or male and female (you'll want 2-3 females per male) this can be bad mixing too much because of cross breeding. Another idea is the species tank. A large group of one fish, and maybe a few odds and others as well. A Psuedotropheus demasoni tank is a common species tank. Not all species will get along with it's same kind though so research this.
Demasoni for example don't do well in groups less than 8.
Personally, A Red Cap Lethrinops (lethrinops Itungi) would make an AWESOME species tank.
What might be a good place to start is just look at hundreds of African fish, pick your favorite, and plan your tank mates around that fish.
Posting a possible stock list on here for approval is always a good idea as well.
Hope this helps, with a 63 gallon, the possibilities are quite limitless. The potential for an awesome African tank... I envy you.
This is my 55 gallon all male tank. I have mostly Peacocks, a few haps, a few Mbuna, one Victorian, and one Tanganyikan Tropheus, I will most likely have some difficulties in the future with some fish that don't mix. Most are juvinille a right now.
http://youtu.be/VHTub4fcJLw