Yes I think Adam's suggestions are good. I see you said you prefer old villages and nice scenery to cities, however I wouldn't worry about going through Birmingham. The combination of Warwickshire/Avon ring's route through Birmingham is quite allright.
We did a combination of the Black Country Ring and Stourport Ring last time in a fortnight, which was nice and steady and a good combination of villages and places to stop off at - Shugborough Hall on the T&M, Cathedral at Worcester, Steam Railway at Kidderminster if you want to see a bit of British heritage. The route through Birmingham would have been the same as the Avon/Warwickshire ring combo as we didn't need to do the Netherton tunnel/Wolverhampton 21. We moored in the centre and it was v pleasant with hanging baskets of flowers etc around the place. The boys enjoyed the visit to the Sea Life Centre right next to where we moored and the excellent take away curry we had!
In the past we,ve done the Four Counties plus Caldon and Macc in two weeks. Again a route of nice scenery/villages and going through Stoke on Trent is worth it for the Harecastle tunnel! We had time to do both Caldon and Macclesfield extensions but of course you don't need to do both, see how time goes, or perhaps you could do the Llangollen as a side trip add on instead?
Enjoy your planning!