You could buy breeches in a non-beige color. That'd make them seem less "fancy and traditional" I have breeches that are dirt colored which I use for everyday riding, they don't look like much but they always look clean =P My friend has plaid ones, they don't look like breeches at all!
I ride in black breeches with black half-chaps and black paddock boots. This get-up goes fine with t-shirts, sweatshirts, you name it. It isn't very fancy at all...especially not once everything is covered with short chestnut-colored hairs! :)
The breeches I have are Tuffriders and they have a low rise. Very comfortable, very easy to clean, and so far, they are wearing like iron.
kitten_Val: I got a Corbette; Charles De Kunffy. I haven't ridden in it yet but I sat in it at the tack shop and it is very comfortable. It really holds my legs underneath me with the leg rolls and the flaps are long enough to accommodate my long thighs. It was new but a few years old and I suspect discontinued because it was on sale for very cheap. Sorry, I can't help but go into detail because I'm so exited about it
I've heard it's a nice one (although I never had a chance to try one - local stores don't carry Corbettes). I hope you'll enjoy it! :)
Thanks everyone, I'm starting feel like I know everything about casual riding clothes now! I didn't realize that there were so many things I could try. I rode in leggings yesterday and they were pretty slippery so I've ordered a pair of black breeches. I didn't even know that they came in black but I agree with you guys, they do look much more casual. I might just try my mom's yoga pants too if she will let me ;)
Kitten_Val: Thank you, I am definitely enjoying it. I hope you found/find what you are looking for.