Sounds like a great collection. You got all the good advice you need in the first few posts from Rhett, Steve and Frank.
As Frank says, if you want to keep them then grading isn't as important. Put them in a secure place and try to learn about them (caution - it's addicting). This board, the Lipset Encyclopedia, plus Old Cardboard magazine - link to OC at the top of this page - are good sources and very interesting too.
If you want to sell them, then Steve makes a good suggestion to go with SGC. People have their preferences, but the hobby in general tends to lean toward SGC a the grader of choice.
And Rhett gives the best immediate advice of all - don't let people here try to cherry pick the best cards for a song. There are a whole whole lot of really good people here that would make you a very fair offer on individual cards or groups of cards. But there are also those few that will spam your PM trying to be first in line for a steal. (I'll bet that your PM area is already starting to fill up with expressions of interest.) You probably won't be able to tell the fair offers from the low-balls, so the safest thing would be to politely decline all for now until you have had a chance to better understand what you have.
If you go the auction route, the auction house may help with the grading process or at least advise on which would be best graded.
You've received good advice in this thread - I'm just an echo!
And you've already done one of the smartest things you could have done, which is come on this board and ask for advice instead of taking them to a local card dealer or antique shop. You'll get better advice here than anywhere. Watch for certain auction house, graders and individual names to keep surfacing in the recommendations, and you'll know where to go next.
Good luck with it. Post scans when you have them.
Joann