PTWolf77 said:
I want an art that will give me effective self-defense. I do not need the arts for fitness; I am a personal fitness trainer and in good shape. I also do not want to do a lot of conditioning at the beginning of a class (no thousands of pushups, jumping jacks, etc.). I don't mind an art with a spiritual side; however I already have a daily yoga practice. I live in the New York City area and have access to a wide range of disciplines.
Ordinarily I'd ask "What do you have available?" but indeed you have lots of choices. One crucial point from previous beatings of this horse: The instructor matters more than the system, so focus on that. But, you need a way to start with all the options you have available. Here's my two cents.
Although it varies from instructor to instructor, arts that tend to do less calisthenics in class and are effective come in all shapes and sizes, but the following spring to mind: Wing Chun Kung Fu, Filipino martial arts (arnis/escrima/kali), Jeet Kune Do, Judo. The FMA and Judo could be done in too much of a dueling/sports fashion, so keep your eye out for that. There are also many lesser-known arts that might fit (Indonesian silat, etc.). There are many other styles of Kung Fu that might give you want you want. In my experience, preliminary calisthenics are common in Karate, Tae Kwon Do, Kenpo, and, frankly, most martial arts schools, but again, it varies, and surely there are many here who would disagree with me on any of these.
Systema looks interesting but I don't have enough experience with it to recommend it. It's worth investigating--its relaxed nature might mesh well with your yoga.
I don't know if you'd think of boxing/kickboxing/Muay Thai/Brazilian Jiu-Jitsu/Mixed Martial Arts in the "conditioning at the beginning" category or no; all are good for what you want but do include conditioning of some sort.
I visited an aikido class, the school was great and the instructor friendly, but I am not sure how effective aikido is for self-defense.
I think Aikido can be good if you have a looooooooong time to invest in it, but I don't think it sounds like what you want.