I still use and just adore both Dream Body sets. If you are looking for more of an inner thigh impact, I would go with the original series (not the cardio); in general the original series seems to have more of an inner thigh focus and the cardio set has more of an outer thigh focus. Also, the original series is a little less expensive since it has been out longer.
The BEST workout for inner thighs in the entire Dream Body series is Fusion Mix with Darby. DARN that is tough for the inner thighs, and lower abs!!
I think just using both series for me (and especially the cardio series, has really improved my endurance, and for overall toning up. InTENse and Barre area great for the arms, the Fusions (Fusion Mix, Fusion, and Fusion 50) are great for the legs and overall toning, MILF has a TOUGH cardio workout and some great outer thigh work, the Tabatas - Tabata & Toning and BataBarre - are really tough and fast paced too. I like the Bikini Bootcamp workouts for a little easier workout - they are more arm and ab focused and just seem a tiny bit less intense.
Some differences between the sets: set 2 allows you to play the workout without the music; easier to split workouts into two workouts; uses the loop band and gliding disks (only T&T of the first set uses the gliders and not for very long). The Fusion Mix workout of the first set uses a stability ball, the only DVD to use this piece. Both sets use a small playground ball, 2# weights, a barre (only for Barre and Batabarre), and a band. First set is more toning intense, second is more cardio intense, but they both have a mix of both.
If (and hopefully when) they come out with a new set, I will pay full price for it. I held out and got the first two at a bargain, but now that I'm totally hooked on them, I don't mind jumping in to the next set at full price. Right now and for the past several months I've been alternating these workouts with Tonique (BTM/ATM/FF), Horizontal Conditioning, and Buti, and running.
ETA: I also go at my own pace too, just like with Tonique.