I have made a New Year's resolution to get into better shape to improve my dancing.

Like most, I have a full time job so don't have a lot of time to devote to an extensive workout.

Specifically, I want to work on my flexibility, strength and balance.

One goal is to (ideally ) be able to do a developpé with complete control, i.e, be strong & flexible enough to PUT my leg where I want it & hold it there versus getting it the via momentum and not be able to hold it.

I have worked with personal trainer but he had no clue on how to acheive my goals. Needless to say, he also couldn't fathom the fact that I want to be able to do this while wearing 2 1/2" to 3" inch heels.

Any ideas / suggestions would be greatly appreciated.

Jvallee

Yoga classes help with strengthening and flexibility, but as phil said, you really need to constantly practice the dance to build the necessary strength ... a little warning though ... the sensation of having your abs and back "burned out" the following morning might not be entirely pleasant.

I've just started a good ballet class in San Jose, CA, and all 3 of those objectives you mentioned are adressed in this class.

I've also had a girlfriend take a private lesson with the instructor, and she mentioned that she has learned how to do a develope properly. "And it made so much more sense" to her.

You might want to ask the pro's or really competitive students, if any of them can recommend a ballet teacher. Having one that understands Ballroom is a tremendous help.

There are no magic solutions!!
There is also a little bit of a paradox in your requirements - you don't have time for extensive workouts, but you want to improve your dancing.
Improving your dancing significantly will take lots of time and practice.
A high level of fitness (aerobic, strength and flexibility) is the only reliable platform from which to develop the specific skills and fitness requirements of the sport (plus, of course, improving your general health). Like any sport, dancing has its specific fitness requirements.
You can of course work on all the elements required - stand on one leg with your eyes closed and this will teach your brain to improve your balance - keep your leg muscles strong - do back extension exercises etc - but at the end of the day, there is no substitute for quality practise (under the guidance of good teacher) of the dancing you're interested in.
I used to have problems with my alignment and balance in the whisk and chassis movement in ballroom, so i developed a practice routine i could do at home on my own, and i did it for 20 minutes every day for many weeks. I have no problems now (not with whisk and chassis, anyway!!) This is the sort of work you will have to do if you want to seriously improve. It all takes time and a serious committment and there are no short cuts. If anyone else has good ideas - - please let us know!!