weegreen - why wouldn't you be able to do weights for a lifetime?
mamac - I think Yoga and pilates do have their place and are wonderful for such things as flexibility and also building core strength. You can honestly do whatever you want. I think though that weights and doing weight training is something every woman should do. There are a lot of benefits, not only building your metabolism but building your overall strength. Weight lifting is also great for building your bone density which helps ward of osteoporosis. You can fit in pilates, yoga and weight lifting without issue.
Also, body weight exercises in general are awesome. If someone told me that they didn't lift weights but could do multiple 'real' pushups, handstands, pullups, etc, I'd say they are much stronger than me