Let me start off by saying that I love the Poly. So I am a little biased.
We have stayed at the Poly 4 times. The last time we stayed in the concierge building. We are off to see the Mouse in three weeks and we will be staying at the AKL and the Poly. At the Poly, we chose the LVC again. I can't say that it was a simple decision. Of course, the concierge is fabulous and based on what I have read about other concierge services at WDW, it seems to be the best (admittedly, I have no first hand experience outside of the Poly's concierge).
If you have a ton of money, it's a none issue. Stay concierge everywhere you go (except AKL, since you could end up with a non-savanah view). But if you are like me and have enough to afford it, but you're not related to Donald Trump or Bill Gates, then money has to factor in. The concierge service does not save you money or even come close to breaking even. The question then becomes is it worth the money. That's a toughie and will obviously vary based upon a number of factors and the value you place on those factors. Let give you the factors I considered and some of the pros and cons (I have the kids today and, therefore, have a lot of time on my hands, so hold on):
1. Room location.
Pros: The Hawaii longhouse has the best location. It is centrally located between the two pools, on the beach, and it is close to the Grand Ceremonial House, the marina and not too far a walk from the TTC. If you don't go concierge, you may be assigned to any of the other 10 (I think there are 11) longhouses. The longhouse was recently refurbished.
Cons: There really isn't any.
Overall Value: Very High to me. We will be spending a lot of time at the resort. So being centrally located is a good advantage. However, if I was going for a shorter stay (we are there for 8 days), then this would be less important. Also, if I was going to Epcot a lot, then I would probably try for a longhouse closer to the TTC.
2. View.
Pros: The Hawaii's lagoon views are the best. Only the Tahiti's come close. Garden views are also very good.
Cons: The second floor rooms have no balconies. The third floor is smoking optional. This can kind of limit your choices. Also, not all rooms have views of the Castle (because of landscaping), though most do.
Overall Value: High for me. We fell in love with our view last time. We have 2 kids, age 4 and 5. After the are down, the balcony or patio provides a place to sit and talk without having to worry about waking the kids. Being able to see the Castle is a nice benefit at those times. As for the smoking optional rooms, we had one last time and I never smelled even a hint of smoke and I am pretty sensative to that. So anything on the third or first floor is fine for me.
3. Lounge and food service.
Pros: The lounge is like having a 1000 sq. ft. family room on your hotel room. It has a big screen tv, games, books, great views and, of course, food. It is a great place to go to escape the rain or the heat. And its great for evenings when you are not returning to a park. The food is top notch, varied and plentiful. Go to Deb's website for samples offerings.
Cons: None.
Overall Value: Average to High for me. Being able to relax in the lounge is very nice. However, we like to try different restaurants as well as return to our favorites. That means there is little opportunity to take advantage of the lounge's food offerings.
4. Concierge staff.
Pros: Very helpful with making PS and other reservations.
Cons: The concierge staff seem no better than the rest of the Poly's staff. This is not a knock on the concierge staff because every single CM I have encountered at the Poly has been friendly and helpful - really top notch. So that is not really a con, but I thought I'd point if out.
Overall value: Low for me. I enjoy planning our vacations almost as much as actually going on them. So we do not take advantage of the staff that much.
As you can see, a lot depends on how long you will be spending at the resort. If you are going to be gone at the crack of dawn and not returing until after the fireworks every night, you are not going to be able to take advantage of much of what the concierge has to offer. If I was only staying 3 or 4 days, and if they were going to be park days, I would most likely get a regular room.
One more thing. This is by no means a summary of the benefits of staying at the Poly, only its concierge level. I guess I assumed that you are definitely staying at the Poly. Other big pluses of the Poly are its monorail location, its restaurants, fantastic staff, the marina and beaches and the overall atmosphere, which really convinces you that you are staying in an island paradise.
Hope this helps. John