WL is a great hotel for what you want to do. However, for a romantic stay at Disney here is how I would choose, keeping in mind that your idea of romantic may not be exactly the same as mine.
The biggest problem that you will have in early September is the weather - it rains a lot that time of year. Wilderness Lodge's primary transportation is by boat - there is a larger enclosed one and a smaller open one. These run you over to the Contemporary's dock or to the MK entrance. At the MK, you can connect to another boat that will take you to the Polynesian or to the GF. The Contemporary boat gives you access to the monorail. These boats shut down when lightning is within about 10 miles of the park, and then you either drive, take a bus, or Uber/Minnie.
Because of the weather, my first choice, if money is not the issue, would be the main building at the Grand Floridian. At the GF, you have several restaurants that I consider to be romantic. At the top of the list is Victoria and Albert's - the chef's table is not really romantic but it is the best dinner that we have ever had. The dining room and the Victoria Room are both (IMHO) the most romantic experiences in Florida. The GF also has Citricos, and while it is not really my favorite you can have a romantic meal there. There is also a great little bar on the second floor that his great for couples whether you drink or not. The GF has a band that plays in the lobby in the evenings, and there is also a piano player several times during the day. All of these are in the main building - no walking through the rain to get to dinner at 6:00.
GF also has Narcoossee's, which has a great view of the fireworks and boat parade in the evening. You might need an umbrella but it isn't too bad of a walk most of the time.
My second choice would be one of the other buildings at the GF, again because it has the best access to several romantic restaurants.
At the time of year you are considering, there will not be as many kids at the hotels, but the GF does have a separate "adult" pool and pool bar area that is great to hang out at. Most kids go to the main pool, which has the slides and water attractions.
Last, the grounds at the GF are romantic to walk, especially in the evening.
WL comes in at number 3 on my list. The northwestern theme is great there, it has a nice lobby, the pool is fun, and I like Artist Point. But it does not have all of the romantic stuff that GF has. Plus, you have to deal with the boat transportation in the middle of t-storm season.
Fourth pick for me would be Yacht Club. If it is not raining, you can stroll on the boardwalk or through the EPCOT countries. Both are nice in the evening. Plus, it is easy to get to Shula's from there. It is not as romantic as V&A, but it is our favorite restaurant at WDW (excluding V&A which is in a class by itself).
Regardless, you will love WL, and if that is your choice, just remember that you may have to be flexible because of the weather.