want to use 2 subs and prefer tower speakers.
Why do you prefer tower speakers?
I find people "think" tower speakers look more impressive in their room, and must sound better than bookshelf speakers because they're bigger.
"Look more impressive in their room" is often true among the uninitiated, (friends, visitors and girls).
"Sound better" is
most often not true within the budget generally utilized by this same crowd.
What I'm trying to say is, you need to decide between "looks impressive" and "sounds good". If you're going for looks, get some cheap towers. If you would rather it "sound good", go for some good bookshelves. You won't be able to beat the Affordable Accuracy speakers in your price range for sound.
And staying under $1k, forget 2 subs. Go with one. You can get a nice one with the money left from 2 AAs. (You do know that 2 subs are generally not intended for more volume, right? Two subs are used for better balance in multiple seating positions, meaning everyone hears the same sub volume no matter where they sit.) So start with one good sub. Set it to shine where you sit. If you later decide it's a problem for one of the other seats, you can save for a second sub... or let the person who sits there buy you one.