Hey Jax, if you want a lot of control and none of the mess I would suggest color pencils to begin with. There is a bit of a learning curve but once you get a few techniques down you are able to produce really amazing results. I have worked with Prismacolor, FaberCastle Polychromos and Blick pencils for many years and have become quite proficient with them. Also water color could be something to look into or soft pastels but both of these mediums can be a bit messy. Another medium is charcoal which produce a very distinct results...or you may want to try them all in a mixed media...but if you are use to the markers and the control you have over them I say the transition to color pencil will be your best result.
Prismacolor makes a great color pencil. I use them alot for my own stuff. If you want to use something different for pen, and ink. Try doing your inks with a winsor & newton 00 sable brush, 02 sable brush, and a dip pen. If you buy a large bottle of black india ink. It will last you for ever.
Thanks for your replies! When I was young I tried colored pencils and did horribly with them so I guess I've always been a bit afraid of them lol. But I love a challenge! So I think I will explore with them again trying a few techniques. And the ink sounds like so much fun! I will have to try both. Thanks guys!! =D