Personally, I'd avoid the gorillapod. ESPECIALLY if you end up getting the 18-200. Too front heavy for such a small thing (I own one and now hardly ever use it due to its flimsy nature).
If you are looking for a travel tripod that is sturdy, I'd go with one of the MeFoto models. I, and many others here, swear by them. Light, easy to set up, durable...and affordable. The one I use is the roadtrip, and I have never felt that I was limited in any major way (it isn't the most sturdy when its "all the way up", but if you are careful you can make do).
Regarding lenses (having been a D3100 shooter myself in the past and now having handed it down to my gf): If you are just getting started out in DSLR photography, the 35mm is a fantastic investment. It performs decent in low light, it is cheap, and it forces you to physically move around and learn composition.
If you are looking for getting some awesome "wide angle" shots, the 18mm may not be wide enough for you...if thats the case then I can suggest either the Tokina 11-16mm f2.8 or the Sigma 10-20 f4-5.6. Both are sharp, waaaaaay cheaper than nikon branded glass in the same ranges, and will work with your camera. They will let you get very wide without having to dip into fisheye territory, and are very well built and have given me plenty of mileage.
Bags: If you are planning on actually investing a lot of money into this hobby (which is easy to do even tho you said you weren't planing on it), I wouldn't cheap out on what you are using to protect it. Personally I like the LowePro brand bags, an AW (all weather) model can save your butt in the case of sudden florida showers. Having owned 3, I can suggest with the most confidence that the slingshot 202 aw is great for the parks. You can strap your tripod to it, and fit all the gear you'd want for the day in a comfortable fitting form factor, that makes it easy to access the inside without even having to remove it.