Daox, my garden is 12x24 just to give you a rough idea of what I have. We planted about 20 tomato plants, (10 of which were my parents...the smaller ones in the pic in my Intro), 3 cucumber plants, belgian onions (given to my by my grandmother who just passed away this February God rest her soul, so these are very precious to me as she brought them back from Belgium a long time ago), 3 rows of beans, 3 rows of carrots, and 2 rows of beats. I personally wish the garden was bigger as I'd like to try some different things, but I love what I have.
My wife does a lot with tomatoes (salsa, jarring tomatoes for use in sauces and what not...both her parents were born in Italy...it's in the genes
). And her mom and her whipped up most of the carrots and beats for baby food for our 4 month old once he starts on solids. I'd say 10 tomato plants is a little overkill for us. And I'm not sure my parents will put any in next year, so I'll have room for other things. I'm going to play it by ear. I just bought a garden book to help me out, and I learned that you can set up your garden to produce certain vegetables during the winter and also plant certain ones in the fall so that they're ready to pick in the spring/summer, so it gives you a wide range to try different things. I may try hot peppers next year for my wife's salsa.
In any case, you should have a big enough garden with a 15x25.