I just created a IFR flight plan from Seattle to Dallas Love using FS. No Dep/Arr so no SIDs and STARs. That way I could pretty much use any runway assignment for departure and arrival. I could see the route legs after I imported FS plan into FMC. The first waypoint I got was in southern proximity of my assigned 34 R for takeoff heading north.
So when I was about 400 ft, I engaged, VNAV and LNAV. VNAV did its job as after establishing +ve rate of climb, my speed was controlled. But I kept heading northward. So I switched to ATC departure frequency and switched from LNAV to the heading I was assigned. After I had made the U turn of sorts, I engaged LNAV again, just to see what happens and sure enough the plane headed towards the first waypoint. From there on the plane followed the route until it was T/D time except that it was ATC that guided me through step descending. I stopped following FMC from there on and just relied on ATC for my headings, frequencies and final approach. Managed a solid landing capturing glideslope but was still unsure about when exactly should I have engaged localizer and approach plus my rate of descend was messy from T/D as I was anxious to get to the assigned altitudes quickly.