Good ideas, Swimmer! I do have Yoga Foundations and a few KCM's I could do 30 min. I was looking at Jessica Smith's Total Body Balance, but then tried one of her walk workouts on youtube, and was unsure. Oh, the choices!
Hi! I think Jessica Smith has a lot of great intermediate workouts and you don't even have to spend a dime if you get them from her YouTube channel. Her walking workouts are considered beginner/intermediate and probably way too easy for a Cathelete, but she has great intermediate workouts on her channel that you can preview first and then choose the ones you like.
If you're not in a budget and want to buy a couple of intermediate workouts then Jessica Smith Cardio Abs and 10 Pounds Down Body Blast are really solid workouts which are circuit based with weights and/or strength moves mixed with cardio blasts. Caroline Pearce's Total Cardio Burn is also an amazing intermediate workout with the same circuit training style as the two previously mentioned. If you are looking for weight training only, Kelly Coffey-Meyer's Your Best Body and Body Shop are really good and again rated intermediate. The good thing about those two is that they are divided in 2 shorter 30ish minute long workouts that target the whole body.
I got two of the Ufit workouts of Cindy Whitmarsh's on my wishlist. They look really good. However, Cindy has an "oldie" (circa 2008) that you can get from less than $7 on Amazon. It's called Results Fitness: 10 Days to a Better Body. It has the format of one of the Ufit workouts (upper body with cardio intervals in one segment and a second segment for lower body with cardio intervals) but with longer segments, Ufit's equivalent has these upper and lower body segments, but they are each 20 mins long and the Results Fitness workout segments are each 30 mins long. Also, Results Fitness is rated intermediate/advanced and Ufit is rated intermediate.
I also wanted to add that all the workouts I mentioned can be adjusted to a higher level when you want to work harder. So if you get any of them you can either use them for lighter days or make them more intense by using heavier weights (if the moves are slow enough to allow this) or do all the segments included at once instead of doing one of the shorter segments so you can burn more calories without getting out of breath.
This list is quite long, I hope it helps. Doing yoga is also a really good choice after STS and you've gotten great yoga recommendations already. Oh and I can't forget Cathe's Slide and Glide. That one is easier but sneaks up on you and best of all great cardio and body weight only strength segment. Yikes and Travel Fit is also good. Hehehe. I probably won't help you much with my long list.
. I own a lot of intermediate workouts and actually like to do them often, when I do advanced workouts every day I gain weight because my appetite gets out of control so I like to mix both types of workouts during the week.