I'm super excited for NL2. Here are some features that I would want to add though. Many are already planned/complete, but here they are anyways. Some of these are more ridiculous then others, and I do NOT expect ANY of these to be in the final NoLimits version (except for some of the coaster styles).
4D, B&M Flyer, Dive Machine, Swinging Suspended, Wing Rider, Timberliners, ZacSpin cars, drifting coasters
Also, an easy(ier) way for people to make their own cars and import them. Reference pieces of track via 3ds models for example.
Ole said he wasn't sure how to do prefabs. If I was him, I'd try to make it so they are "separate" types of track pieces then the regular ones (i.e. they don't have verticies except on both ends), that way they couldn't be screwed up as easily. Also, a build-in prefab editor would be nice. Right now, putting in prefabs is a pain on the @$$, as it often screws up a lot of track before it (this is the same in scream machines by the way). A WYSIWYG-type prefab placer seems crucial, so you could automatically "see" which peices would go where, and their relative size. Perhaps a "new" track piece could be lead-in, which automatically creates a connection and updates smoothing/banking between two track pieces (including prefabs), without altering the pieces it is placed between. For example, if you had a 180 degree turn from a brake run into a station, by changing the piece type of the curve to "connector", it would automatically smooth itself to make sure both the station and brake run were still straight, but they "flowed" into each other smoothly.
More Ride Statistics: including numerical values of overall intensity, excitement,dizzy-inducing-ness, etc, just so its relative to other tracks.
Locking Pieces: Perhaps an option to "lock" verticies, so they couldn't be changed, only moved. Maybe also an option to lock their position as well
Scaling Elements: Let's say you have a turn, but you need it to be wider. Perhaps you could select the vertices making up the turn, hit transform, and then a box would come up letting you rotate,/scale/skew the selected track. I guess it would function much like photoshop in this sense:
Scenery Integration: Ability to use a grid system to place 3ds objects/3d models or align them with the track.
"Easy Edit" mode: a mode for beginners form RCT who can just string together prefabs without having to worry too much about complex hearlining and forces.
"Ride Wizard" mode: select a coaster style, a list of elements, max g-force, height, length and type (twister, kiddie ride), and the program will build a rough overview of a coaster. From there, things could be edited to be more smooth. Or perhaps even a random-all button (aircoaster for iphone does this).
Online Browser: If anyone here has ever played Garry's Mod, I believe they have something called the "toybox." Basically, its a window in the game that allows people to download (temporarily) any user-created thing uploaded to the toybox servers. Its pretty much a cloud service for the game. It would be nice if tracks, prefabs, etc, were done in the same sort of fashion; from straight in the game you could ride tracks w/o having to download them permanently, and rate them on-the-go. This could also be great to have a voted "track of the week," that everyone can see and download on the front page. Of course, if you're offline, any you haven't downloaded wouldn't show up.
Other random ideas:
create a custom soundtrack to be played either synced to the ride or unsynced to the ride.
Particle effects/ride trigger points for animations (like you add a trigger much like a support, and link that trigger with whatever animation/particle effect)
Prefab supports/normal supports that have collision detection.
Align side-view camera to a track piece's axis (so if you were building a loop at 45 degrees relative to the top view, you could easily edit it sideways without having to guess too much)
Be able to start "ride" at any given point and loop it.
Transfer Tracks that function as lifts/tilts/freefall sections (like th13teen or whatever its called)
G's viewable in editor window.
Separate Sliders for visual wear-and tear and overall track bumpiness
Share/save color schemes for cars and tracks
More station buildings
More lift types (cable, fat chain, covered chain, magnetic lift)
Adjust friction for specific pieces
1st person mode (where you "walk" around the queue/on the track)
More then one track on map/ability to sync coasters to each other
On-ride photo piece (doesn't actually take pictures using webcam or anything lol)
Waterfalls and fountains and such
Build a car (choose type of car/base car, type of restraint, type of seat, etc.). Nothing crazy, but you could change restraints on certain cars for example
More launch types (LIM, LSM, Magnetic, Air/hydraulic, water-launch
RCT import (if legal)
NoLimits 1 backwards compatibility (unless its difficult)
NOTE: I've included a picture as an attachment of an idea for the browser for stuff. When you have a lot of tracks or prefabs, it is nice to have some way of organizing them. Here is a suggestion for just prefabs, but tracks could be done somewhat the same.