Doc, I'm partial to the Innovate stuff. You can datalog multiple discreet and analog inputs (TPS is especially helpful, RPM, manifold vacuum, etc.) with their auxbox and a laptop. You don't have to buy everything at first, either. You can buy the basic LM2 kit (or used LM1) and add the auxbox later if you so desire. This setup is something you probably wouldn't want to leave in your vehicle permanently. The basic kit will allow you to read (or datalog) the AFR; the addition of an auxbox will allow you to add other data to the graph.
In your case, you might want to permanently mount an O2 gauge in the cockpit of your motorhome. An Innovate LC1 along with a gauge of your choice would be good in that application.
I look at it this way - the LM2 (or LM1) lives in your toolbox, much like a scan tool or dwell tach. An LC1 lives in your vehicle as an add-on gauge, such as a tach or oil pressure gauge. The first thing to decide is if you want a tool for diagnosing multiple vehicles or an O2 gauge for your motorhome.
The guys here are also having good results with other brands of equipment.
