If you like contemporary, West Elm is a good place to start. The way to get the max length out of a sofa is to keep the arms very tailored, straight - not overstuffed and puffy.

Ikea has the Kivik loveseat. Looks comfy enough to stretch out on and is only 75" wide.

Or check Pottery Barn's sofa finder. They have some really nice options too. For a small space it's usually best if you get a sofa 'on legs', so that it doesn't visually block the space but you can see the floor going through under it. And indeed, armrests not too bulky. Depends on your priorities :-)

http://www.potterybarn.com/shop/furniture-upholstery/sofas/sofa-finder-sofas/?cm_type=lnav

Look at ballard designs - they have some elegant pieces with low arms in apartment sizes that live big.