For abs and overall toning, I really enjoy Gunnar Peterson's CORE SECRET workouts. They are done on a ball with some hand weights for some mouvements (you don't have to use the weights on some of the exercises - it's optional).
It's "tops" in regards to hitting the core of the body (the mid-section) at all angles as well as working the entire body with the help of "functional fitness movements".
If you go on:
CollageVideo's websiteYou can search by instructor and enter the name Gunnar and click on GO. You will get a list of results and if you click on each link that shows up, you will get details on all his workouts, as well as be able to preview online a 60 second clip of each. That will give you a bit of an idea as to how his workouts are.
He's awesome, he's fun to workout with and he's the trainer of many Hollywood stars and runway models who go to him to be in top shape for bikini "shots" in movies etc...
My big ball (you can buy it as a kit with a pump etc) is in storage right now because we're in between houses (we're moving in a few weeks) and that is the one workout series I've missed the most since my stuff has been in storage. I love Gunnar!
I also have Winsor Pilates, but it's different and, in my own opinion, although excellent and quite effective, it's just not as much fun to do as Gunnar's workouts.
I hope this helps a bit!
As for "stretch" workouts, I really LOVE the "AM and PM Yoga for beginners" by Rodney Yee. Also sold on CollageVideo.
The AM Yoga segment is a fantastic stretch to start your day. I actually also do it at night, it feels sooooo good. Rodney Yee is "tops" in the world of Yoga and his videos are filmed in beautiful outdoors surroundings. The PM yoga session (both are on one single DVD) is done by Patricia Walden and is a fantastic body stretch, especially (but not exclusively) for people who work at computers. Our upper bodies get drawn forward and cramp up while working on computers all day long, so she aims at opening out the ribs and chest and stretching out the arms and the rest of the body to pull us "back" into a healthier body position. It's a very soothing and short session. Both are approx. 20 min. long but you touch on everything. I always go back to that DVD.
P.s. you can also search for specific types of workouts on Collage and you might come across other intersting things as well. You can also call them on their toll-free number and each person that works at Collage has done the workouts and can really help you choose something to your liking.
Good luck!