Karen, the real bottom line is that the condition of your floor will ultimately be the deciding factor as to whether your floors are worth restoring. Hardwood floors, oak or ash or whatever, usually are, unless they are in such bad shape that they cannot be restored and must be replaced. Even if that is the case, and you want to spend the money, I'm sure that you can have your floors replaced in kind.
I think that your next step would be to order a copy of the November, 1999 "The Family Handyman" magazine by calling 715-247-5060 from 8am to 5pm central time. If they still have them, the cost will be $4 or they can supply photocopies of the great article on restoring hardwood floors for $3.
Then you will be armed with knowledge when you call 3 to 5 professional flooring restorers for quotes on doing the work. As you will see from the article, this can be quite difficult and involved, or it can make a good project for a couple of weekends. That depends on your level of experience with similar projects, your desire to do it right, and your realistic budget. This is something that nobody but you can answer. But, again, you will be armed with prior knowledge of what's involved and an understanding of the process.
If you choose to have it done, you will probably find that the pro's will want more than you thought and that their quotes will be grouped with 1 or 2 on the low end, 1 or 2 on the high end and 1-3 in the middle. Check to be sure that they are giving you prices for the same level of quality of work and materials. If not, ask them to requote based on doing the level that your knowledge and what you have learned from asking them questions while they checked your floors to prepare their bids. Investigate the ones who quoted in the middle with the BBB and their references. The one's on the low end are might be looking for work because they do shoddy work or just the economy, but, what it says in the newspapers aside, most places should still be brisk. The ones on the high end are so busy that they don't want more work. Now the decision will be up to you.
It sounds like you have a real treasure. Remember that this is something that can add a lot to the resale value of your house. I'm sure that you want to take good care of it, keep it if at all possible, and replace it in kind if you must.
Good luck and let us know if you have further questions. You can also search the board for prior posts about flooring or more specific issues if you get pressed or don't understand something.