Depends where you want. Have a look at www.sailscotland.co.uk. This is mainly yacht charter but there are two or three motor cruiser operators.
The Clyde is a good area to try if you have'nt been here before and can easily take 2-3 weeks to explore properly. Loads of scenery, marina facilities, sheltered anchorages and good restuarants. Lochgoil cruisers charter some sound but a bit elderly single engined Brooms - 8knts max.
The Clyde/West coast is spectacular and if you want a list of good ports of call or an itinery for a particular timescale give me a shout.