In reply to Johnny_Grunwald:
You have plenty of options which may work for your group but I fear your initial thoughts about peaks may not be appropriate. How much experience of the Cullin do you have yourself? It's not like anything else in the UK. When you say mixed ability I have visions of scrambling being relatively new to some group members.
Route 1: All the peaks you mention involve potentially serious scrambling which may be beyond the scope of a confidence rope if someone needs help. For example, the easiest way up and down Sgurr nan Gillian is the so-called tourist route (SE ridge), a grade 3 scramble with serious exposure in places. The SE ridge is more serious than most mainland scrambles. All other descents will probably involve an abseil at some point.
A suitable alternative from Sligachan for those new to the Cuillin could be doing a round of the Fionn Choire. For this, perhaps consider going up Sgurr a Bhasteir (not Am Bhasteir) and then working your way up Bruach na Frith then either down into Fionn Chorie or down Bruach na Frith's NW ridge. Sgurr a Bhasteir gives a pleasant introduction to scrambling on the Cuillin, with quite a few of the difficulties avoidable but also plenty of options to keep things interesting. Going down the NW ridge is perhaps a bit more continuous but of a similar vein. If the mist's not in, then you'll get excellent views of Pinnacle Ridge, Sgurr nan Gillian, Am Basteir and its tooth.
Route 2: There are a few options from the Glen Brittle side, but it's hard to make things circular without getting involved with some serious scrambling and route finding. Accessing the Cioch is quite serious so should probably be ruled out with a mixed ability party without a climbing rope. Sgurr Alaisdair, one of my favourite peaks in the Cuillin, is a possibility as a linear walk. This would involve going up and down the loose Great Stone Shoot. (As with all Cuillin adventures, make sure you take a helmet.) There's a short-lived narrow ridge from the top of the stone shoot to the summit which is grade 2, which you would have to do out and back.
An alternative, circular route on the ridge may be doing a round of Coire na Banachdich. This would be particularly suitable if the scrambling on Route 1 went well and you found it within the group's limits. Here, you could do a scramble up the South-West ridge of Sgurr Deag and have a look at the In Pin from its summit. Then head north to Sgurr na Banachdich which will take you on some scrambling ground but often with the most difficult parts avoidable on narrow paths the west (left going north). There is then a path off the summit of Sgurr na Banachdich that takes you into Coir' an Eich, from which the rest of the decent is obvious. Finding the way off Sgurr na Banachdich can take confident navigation skills if the mist is in as the broad shoulder can feel a bit confusing.
Regarding maps and guidebooks: the 1:50K OS map is okay on the Cuillin but the 1:25K is almost impossible to use due to the overprint showing that the ground is predominantly rocky. The ideal map, however, is the Harvey's Superwalker, which is very clear and has a 1:12.5K enlargement of the main ridge. If you don't already have it may be worth getting a copy of the Skye Scrambles guidebook published by the SMC.
Hope this helps. I'm sure others will be along with more advice.
Mehmet