Laminations alone won't inherently make a neck stiffer. Although it's arguable if stiffness is really a serious problem with most typical bass neck designs.
Laminations have a few advantages:
- Visual impact. You can get a really cool look. It gives you another design variable in terms of getting an overall appearance you like.
- Stability. If you carefully choose a one piece neck blank, it can be stable. But with laminations, you have the chance to make a REALLY stable neck. Laminating a neck blank can let you use wood choices that people may be hesitant to use in a one piece blank, since you can mix them with something known to be typically more stable. (for instance, you can use a stripe of flame maple, even though flame maple is often less stable than straight grained wood.)
- Blending characteristics of wood choices. This one is probably a little more of a gray area, but if you associate certain sounds with certain wood choices, laminating your neck gives you the chance to mix different qualities.
If you are building for stability, you need to keep a couple things in mind:
- Regardless of if you're doing laminations or not, you need to make sure you have good wood stock without a lot of runout or other issues. And it needs to be stable in terms of moisture content.
- Most laminated necks feature a symmetrical design. You neck will be most stable if you cut the strips accounting for this. For instance, if you are going to build from a 1" thick blank, and you want a 3/4" wide maple stripe on either side of a center accent stripe, you can start with a 3/4" thick maple board, and cut two 1" strips from it, then turn each on it's edge to get your 1" thick, 3/4" wide strips. If you cut the strips from the same rough board, and you cut them adjacent to each other and then rotate them "towards" each other (left strip clockwise, right strip counterclockwise) you will position them such that any natural instability in the board will cancel itself out. For instance, if that board had a tendency to bow upwards, you've now got two strips oriented such that their tendency to bow will "fight" each other end (usually) end up with a blank that doesn't move at all, instead of a single-piece blank cut from that same board that may have bowed.
That last part is key, you don't want to just stack up a random bunch of strips from random stock, or you'll end up with a crapshoot in terms of the stability of the blank. But if you cut strips and orient them carefully, you can use this cancelling-out to ensure the blank is more stable than the stock you cut it from.
I know that others may disagree with this, but grain orientation (flat vs quartered) isn't important, if you start out with well dried stock and you orient your parts correctly. Quartered wood is just flat wood turned on edge after all. I do like the look of quartered wood in a neck, so I do usually try for it.
In terms of what species to use, that's really up to whatever will look good in your design. You mentioned maple, which is a good choice (it's not the stiffest in the world, but clearly it's plenty stiff enough for a normal bass neck). I like thin walnut laminations between maple, or thick cherry strips alternating with maple, with thin walnut strips in between them. Purpleheart looks really good next to maple as well, and it's super super stiff. Some people use Wenge next to maple - I have a bass like that, it looks good but I'm not super fond of the difference in texture.
I've been doing a lot of building with only domestic hardwoods lately so my last few necks were mostly maple, walnut, and cherry:
