I have the Wide 128, chosen because I like the wider display, and I thought
the price was about right. The next model up (I forget the name) gives you
optional speed and water temp, but you need to purchase an additional
through-hull sensor. The Wide 128 gave me what I wanted, so I went with it.
The Wide 100 has, I believe, the same display size as the Wide 128, but
the 128 gives extra data about fishies (to better amuse the kids) and,
of some importance, details on bottom hardness - useful when anchoring.
-- Eric L. Pederson P-19 #970, Necessity Bloomington, MN