I did enjoy A Libertarian Walks into a Bear! I'd consider it a good Christmas present possibility for my own dad (dads may vary).

A Suitable Boy is very long, but the chapters are short - most of them under ten pages and quite a few that are two or fewer. So one approach might be to just accept that it will take forever and read a limited number of chapters a day - so it won't get in the way of other books you might want to read in the meantime. I hope you enjoy it, whenever you get around to it!