There are plenty of interesting things to use the mana on. Ore production (orechid), dungeon loot production (loonium), or chasing that SS Terra Shatterer come to mind. Or if you're a bit more 'modest' in your desires you could always just go for a set of Terrasteel armour and equipment. And just like with any energy-producing system, you only need as much energy as you'll use. If you're "not using the mana for anything interesting" then you're creating too much mana.
As for aesthetics? You can make some pretty damn pretty mana generation systems. I've seen many setups posted on Reddit. I've even seen a pretty slick setup (ab)using aer-infused fire from TT that's more than a touch amuzing. It's designed to *be* pretty and worth looking at ... if you like flowers. And if you don't then, and pardon my bluntness, what the fsck are you doing using Botania!? If you want the same old boring techy energy gen with generators/dynamos/engines that a mass majority of mods use then use those mods instead!