I want to thank everyone that has replied. You are REALLY helping my wife and I make our decision. We are 95% sure on the Poly (I am picking up the Disney abbreviations!). Given the age of our girls, it seems like that is the place to stay. I should have mentioned that this is also to celebrate my wife's 40th birthday! So my next question, club level or not? Is the additional cost worth it? (not that my wife isn't worth the extra money...just in case she is following these posts

)
As far as Poly vs. BC for a first visit, I agree with the others that Poly is a great resort for first-timers. Take a look at GADisneyDad's links above and I'm sure you'll fall in love with Poly! But just to add a side note, don't take BC out of the equation for your next/future trip. When we first started going to Disney, we stayed at the monorail resorts too, until one trip while in Epcot, we discovered the walkway to the Epcot resorts and immediately fell in love with that area. Thus, our next several trips were at all 3 Epcot resorts, and it was easy for us to figure out that BC was the right resort for us. We are odd (apparently, lol) because my kids loved Epcot and we had a lot of fun in that park. And while many feel that the BC pool isn't great for toddlers, we felt the opposite - it was by far the best pool for us straight from baby stages right through end of toddler stages.
Having said all that, I still vote for Poly because since it is more immersed with the Magic Kingdom and views of the Castle, it will be more of a Disney "wow" for your first time. Save the BC for next time!
Now onto your CL question - if it's in your budget, I would definitely book it. We've had many CL stays there. Our favorite perks of CL include taking advantage of all food offerings and having our choice of juices, water, coffee, tea, soda, beer, wine, and especially their PoG juice (adult version offered too). Also, both Poly pools are steps away from your room, so you can go to either pool and easily back and forth to your room. If you can swing booking a room on the lagoon side, they have spectacular views! Can't think of a better way to start and end the day

.