[nullified]

LTspice [0] is an excellent (and might I add free) SPICE simulator. Linear includes proper models of the majority of their chip lineup, including LED drivers. Their power supply IC models are also excellent. You can simulate a full LED driver circuit and a whole lot more with LTspice. TI also has a similar SPICE simulator [1], but it's not nearly as good, and its simulations are much slower and a bit more unreliable.

I design electronics for a living, and I use LTspice all the time for power supply and analog circuit simulations.

[0]: http://www.linear.com/designtools/software/#LTspice

[1]: http://www.ti.com/tool/tina-ti

[vonmoltke]

Worth pointing out too that most major semiconductor vendors provide SPICE models for their parts. Maxim, for example, has an extensive set of models for their chips: http://www.maximintegrated.com/design/tools/modeling-simulat...

[Scene_Cast2]

Thanks, that helps a lot! Giving it a shot right now.

How long should it take to make a high-power (3A+ @ 3V, buck-boost IC) LED driver, very approximately?

[nullified]

If by "make" you mean create the schematic in LTspice and simulate it, then I would guess about an hour or two (mostly because this might be your first time using LTspice). If Linear has a part that already meets those requirements, it should be a very straight forward affair.