Look at the thymes - they are beautiful - different leaf colors and flowers. Also, the smaller dianthus.

A trip to Well Sweep Herb Farm in Port Murray would give you a great idea of what is available for your type of site.

Thymes and Dianthus arent ground covers . Try Creeping jenny , it spreads fast and has beautiful yellow flowers . Rick

I'm sorry to dispute you, Rick, but thymes and dianthus certainly are ground covers. I've used them as ground covers for years. Do an internet search for "low growing ground covers" and see what comes up.

You can plant different sedums - Dragon's Blood, etc. They are not really flowering but you will save money and water on maintenance.
I live in the same area and would share some plants with you if you are interested.

You may want to try creeping rosemary: drought tolerant, fairly hardy, drapes, great smelling, culinary uses and sports tiny periwinkle flowers.

Agree with njtea, there are lots of great varieties of thyme, including lemon and lime. They're low growing, great spreaders, take to being sheared if they grow tall, and are cold hardy. I kept some in a pot outside all winter and its the best looking thing in my garden!

Yelena, I, too, am in the vicinity of Long Valley - unless you are fenced, how do you keep the deer from eating the sedums?

njtea,
Actually sedums are the ones that were never eaten by any creatures invading my property. I had very bad eperience with fruit trees, azaleas, tullips and vegetable garden, but not sedums, especialy Dragon's Blood. Also I have ground-covering yellow evening primrose I adore - no problems whatsoever.

I love the creeping thyme seeds I got from Park Seed. I have it around my pond and it looks great and takes abuse. It spreads quick and transplants easily but is not invasive. It does die back in winter but looks nice here from May to October. It really is a great anchor for other plantings.

You might look at ajugas, oreganos, creeping phlox, veronicas - waterperry and georgia blue, hens and chicks, sedums, epemediums, forget me nots, fragaria - pink flowered strawberry, sweet flag, pachysandra, foam flowers, lamium, lamb's ear, sweet woodruff, vinca, variegated false solomon's seal.
There are a few ground hugging shrubs too but that may be more expensive like deutzias, a dwarf forsythia, cottoneasters.
There are many. Would help to know what your vision is.
15' x 50' is a lot of space.
Any groundcover you use, you should check how aggresive it is or you will have problems retaining it.

creeping phlox is very nice cascading over rock walls and it is evergreen, too.