I have in the past, and now that I have a garden again, I fully intend to.

What will I save, and why?
Varieties are such a personal preference, but I think right now that I will save seeds from all my OP plants, just to have a safety cushion. Until I have established my collection I think it's good to have a back up that, while maybe not a favorite, will provide something. For instance my dog wiped out most of my seedlings this year with her tail, and I have been scrounging to find replacements. Had I had a stock of saved seed, I could have popped in some new ones and been back on track right away. Once I have a good base of seeds saved, I will probably begin culling based on performance, vigor, and taste (in no particular order).

Why am I going to save seed?
Money. As much as I'd love to be able to save seeds to collect, catalog, and preserve lesser known or endangered varieties, at this point in my budget it boils down to money. And to have seeds to trade for more varieties, of course ;)

When I saved seed in the past, I wasn't very cautious about preventing cross pollination, and once in a great while I had a surprise show up, but in general no, I didn't notice much variation that I hadn't selected for. By that, I mean only planting the earliest emerging seedlings, and saving seeds from the healthiest, earliest producing plants. I think after seven years of seed saving, I got my tomatoes to come in about a week earlier lol. However, I did notice that some varieties went down hill after a couple of years in regards to performance and health, while others seemed to become acclimatized to my garden and performed better and better each year. I even had one, I can't remember which now, survive five scorching weeks without water (while my mother was ill) only to throw it's gasping, wilted leaves up on my patio and present me with three tomatoes, to save seed from of course!

This time, because I have scrounged mostly hybrids and they're mixed in with the heirlooms, I'm going to bag the blossoms. I don't mind a surprise from two OP's, but an f1 with a hybrid parent could be ugly.

Thank you for the interesting questions!

If I may, why not save seed?

I save seeds for several reasons. The most important is that many of the varieties I grow aren't available commercially. If I want to grow it again, I'd better save seeds. If I have saved seeds of an uncommon variety, I can share those with other growers. Then there is cost. I don't want to buy 20 packets a year. I grow out 12 to 20 varieties a year from among the 100+ varieties of which I have seeds. Saved seeds last for many years. Finally seed saving is fun. There are directions in the FAQ's above.
Happy Gardening!
Jim

I saved seeds for the first time last year. I saved them because they were from plants given to me and from Freecycle and I loved the fruit I got from them. Yellow and red. I was amazed at how many viable seeds I got. I think this year we may try heirloom tomatoes from farmstands and if we like them we will save the seeds.