Most of the charter companies are based in Marmaris, followed by Goçek and Bodrum. Sun sail is based in Orhaniye. (Swagman, I'll send you a separate PM on this)
First of all you need to decide where to go.. In one week or 10 days you can either cover;
1-Fethiye, Kekova, part of Göcek bays..
2-Göcek bays, they are so many and awesome..
3-Marmaris, Çiftlik, Bozburun, Orhaniye
4-Orhaniye to Bodrum the Gokova bay
And to decide which option to take , you should put yr preferences:
-easy, short distance sailing, don't mind motoring quite a bit, swimming > Option 2
-keen sailors, exceptional landscape, swimming not on top of list > Option 3 or 4
, swimming, snorkelling, archeological sites, Option 4
Now to conclude, given the distances, ıf you choose Option 1,2, and 3 you need to find a company in Marmaris. You may try Offshore
Sailing, Sun Charter, Yıldız. EGG in Göçek can also be an alternative particularly for option 1 and 2.
For option 4, you may go for Bodrum or Orhaniye based companies. Offshore
Sailing and Sun Charter are also delivering the boat to Orhaniye, Selimiye, etc at extra fee.
Last note; if you come in Spring, 1 and 2 could be better as the rest of the area could be quite chilled at night and sea water
barely around 20 degrees C. Whereas, you may expect milder wheather in Göçek and Kekova.