I have an elliptical and I absolutely LOVE it! If you plan to run outside then an elliptical is the perfect choice for cross training. It makes sense to have a low impact option.
I don't know how much you want to spend, but when it comes to elliptical machines I really think that you get what you pay for. I have a Precor and it's a fantastic machine, but the model I have (5.23) is older and has been discontinued. I was just looking at the newer models and quite frankly, I prefer mine. If I was going to buy another one I'd look at an Octane. They have wonderful reviews and I've been told that they are outselling both Life Fitness and Precor for the home user. Of course, there are several other brands to choose from as well, but I'm not familiar with them. My single best advice is to try several machines before you buy. Every elliptical is different and what works for me may not feel good to you. One thing in favor of the Octane is that you can adjust the stride length.
I'd love to get a spin bike. Rowing machines kind of appeal to me, too. Have fun shopping!!!
P.S. If you get a cardio machine be sure to invest in some audio workouts. I HIGHLY recommend Cardio Coach!