I would regret not posting some Penguin books as inspiration after my recent trip to Oxford and London. It was interesting to walk into Borders in the UK and see all their different designs to our American versions (but that's not really what we're talking about). I walked into borders and saw several of the Popular Classics books. They probably had about thirty or so titles and they were all the same green with titles, author names, and logos in the same spot. I love these covers, but is it a good idea to make all your covers look exactly the same? There was no way I could identify one of the titles from another, unless of course I went in and took the time to read them. I do not know, it is simply a question. I do notice that Penguin does this often with several of their titles (of which I love all the designs).
While in the UK I also noticed that several of the paperback books used a very nice uncoated and toothed stock (something that made me very jealous), several of the titles used hand lettering, and everyone said "cheers!" to each other.
I do recommend looking at several of the UK stores to see what type of design they are doing on their book covers, several of which are some very good options. Simple sites I know of are Borders UK and Amazon UK.