Is Invisalign Worth Having Done when in Your 50's?

Yes, Invisalign is an option regardless of your age.  What I'm more concerned with is the fact that you mentioned you have had extensive dental work and that you say that your teeth are "crowded, crooked and discolored" along with a bridge.  You are right that a bridge can complicate Invisalign treatment.  Invisalign may be an option for you, along with replacing the restorative work you had done 15 years ago and restoring your bite and smile all at the same time.  Seek out a couple of dentists who have extensive training and experience with both Invisalign (or orthodontics) as well as restoring complicated cases to see if you will benefit from a combination treatment.

How much is a beautiful smile worth? One is never too old to improve their smile. Invisalign is a wonderfull way for an apprehensive adult to straighten their teeth and achieve a beautiful smile. Age should not be a factor in your decision.