LNAV/VNAV not coming on I've seen in PM... Can't for the life of me remember what "fixes" it though; I think you need to have a fully programmed FMC/MCP for them to engage (trouble being, 737 and 747 have totally different but strangely similar auto-flight mechanisms)
My personal "preflight" on the 737 (assuming ADIRU ALIGN completed) is:-
1. INIT REF and POS.
2. ROUTE - set start and end fields, intermediate save, enter route, intermediate save, set departure (assuming dep rwy known), complete route save.
3. PERF - set weights, reserve, econ, cruise alt, cruise winds and cruise temp.
4. TAKEOFF - select take-off and climb thrust profiles (TO and CLM-2 in most cases), set T/R ALT.
5. Final page whose name I can't remember or find - set T/O flaps (5deg usually), run down the V speed LSKs to calculate and set them.
Pre-flight complete, set rwy heading as MCP heading, set first altitude limit as MCP ALT, turn on both FDs and arm AT, set autobrake REJECT, engage LNAV, taxi to active, engage TOGA, fly...