For newer ACPI laptops,
machdep.lidsuspend=1 sysctl(8) will allow you to suspend when you close the lid.. add it to
/etc/sysctl.conf if you want the change to be persistent.
A fix went in for this after 4.8 that fixed several laptops that this didn't work on, 4.9-beta is in the release process now.. so.. try a snapshot and see if that works.
Also, if you configure
apmd(8) to run at boot.. you can suspend by using
apm(8)/
zzz(8) as hinted at by backrow.