Not sure I would put grasscloth next to a fireplace due to heat and singing issues. The bookshelf idea sounds nice.

Here are some ideas for you. If you don't want to clad marble on the fireplace, you could consider a brick/ painted brick fireplace too. Since it goes all the way up, it would be a good idea to make it a focal point. I'd also recommend you make use of the high ceiling and add a statement chandelier that matches whatever aesthetic you choose.