Is my room going to suck

I agree with the long wall/near field, a rug...Room sounds 'live', although that can a positive with some speakers.  I'm a big fan of active eq and 'going flat' in spaces like yours.  Your sub will definitely 'rule the room', so keep it leashed. ;)  Some restrained treatments would help, but those are always long term experiments....

May as well make it 'kewl' to look at, since it sounds already like a retreat. ;)   As with the 'newbie' about, I'd be surprised if you couldn't use one....*G*

Both of you. *L*

I also have a small child 17mnth daughter ( my world ) and my listening room is directly below her and our ht room is right next to hers .so i get it 8 pm its pretty much over . Many years ago i had a basement setup similar size . I had some treatments like heavy curtains i did put a large remanant carpet on the floor . I had maggie mg2 a sunfire and cj tubes from a linn lp12 maggie arm . It sounded great for what it was . The basement will buffer alot of the sound throughout the house . Look at it like i do , you still have a space ! and you have a little one too . Although i cringe when she runs for my wharfdales in my ht room lol .. Noo finger pokes !!

You can make any space work given the right acoustic treatments, gear, speaker placement etc..  I've had numerous dedicated audio rooms in the last several houses we've lived in, various sizes and I made them all work.  Some of course sounded better than others depending on what I had to work with.  Always a fun challenge.  
I just make that room a top priority up front before we move in so there are no "eminent domain" convos later.  ;o) 

My 3 kids aren't allowed in the audio room under any circumstances.  It's just easier and less stressful that way...

The auto EQ on your sub should help.
Maybe not your cup of tea, but you can get $100,000 SQ from $8000 in a good headphone/amp setup. (Think Abyss and Woo WA5LE)
No more 7 mo olds here, but the rest of the family is happier when I use my headphones late. Difficult room dimensions, for sure.

It should work out well. George Cardas has developed some very useful speaker placement formulas for rectangular rooms.  Check it out.

http://www.cardas.com/room_setup_rectangular_room.php

Best of luck