Hard to tell unless the piano has been evaluated by a tech in person. It it's 6'11 total, its a Model B. Nice piano. If it has real ivories, its at least 60 years old. Unrestored in reasonable condition, it could be worth 10-15K. Again, hard to tell. Might need strings, hammers, a rebuild, finish. They could be had for less. A mint B, restored, regardless of age goes for appx. 35 to 45K with the traditional style (plain) and 55-65K if it has a fancy Chippendale or Louis XIV style.
Shop around on
www.pianomart.com or check out restored models at
www.countrypianos.com to get an idea of what used private sale and restored models go for..
Be advised, many folks think just because its a Steinway and they see others listed at 4o grand, they think theirs is worth that too and ask far too much. Again, it really depends on its overall condition.
Oh, and if the action is sluggish, have it regulated by a good tech for around 500-700 bucks. Don't throw the baby out with the bathwater. Regulation should be performed every 4-5 years with constant use.
All the best