Silver Majesty question

I am now in a position to put my books out in print through a Print on Demand company called Lightning Source. I thought that signing the contracts would be the hard part, but now I'm not so sure.
For those of you who have read Sherwood Smith's book(s) Crown Duel, you know that she combined the first two books of that series in a single book printing. Now I'm wondering if that would work for Silver Princess and Silver Majesty. Silver Princess is the shortest, but comes out at over 150 pages when adjusted to a 5"x8" format, which is what will happen when it gets printed.
I haven't adjusted Silver Majesty yet, but I'm worried that putting them together like that will result in a monster of a thick book that really won't fit in an ordinary pocket/purse, etc.
Now I'm polling the audience. Put them together? Or print them separately? And why?