Hey Mick,
All of my Vettes are basically driven like yours. In a garage most of the time except when being driven. I have the same cover on my '69 that I bought for it 20 years ago and it is still doing the job.
For indoor use, I like the plain cover with a soft flannel interior to protect the cars finish. I have one for all three of mine. The last one I bought was for my Z16 too. I can't remember exactly where I got it, but I think it may have been from Zip Products. I took a look at this link and it looks like the one I have for my Z06 CE.
http://www.zip-corvette.com/ProductDetails/ProductDetails.aspx?pid={b0fa2945-e13b-47ec-a46f-1dde144c8c29}&gid={710b8d27-125b-4ea4-954d-307efab5efe5}&GroupName=C5+Car+Covers&pname=97-04+Premium+Flannel+Car+Cover&Referer=&Alias=&ptct=SGR-SR&CTitle=&
If you look at other Corvette suppliers (Corvette Central, Mid-America, etc), most of them have some sort of Premium Flannel cover. They typically run between $120 and $150. There are a lot more expensive covers out there, but for the type of use you are talking about, you don't need anything more than this. Unless, you want a cover that is more decorative.
Well, I hope this helps!
Rich