It sounds like a nice glossy warm chestnut would suit you. Then you can have shine without the colour lookinf too flat. If you're unsure you could just try a semi-permenant one designed to wash out in around 25 washes, then you can experiment. Most salons do free colour consultations, you could always pop in to your hairdresser, talk colours with her, find one you like the look of, then go to boots and buy a similar sort of shade. (or obviously just have your hairdresser do the colour if you don't feel confident).
You could Also try Henna, Lush do Henna in brown, and a more reddish-brown, as well as black. Henna won't stain your hair in the long term, but you can't dye over it with chemical dyes.
Good luck! I couldn't live without hair dye, my hair is the same sort of shade as yours, but is dyed a mahogany red colour.