I have a amd64 pc and a i386 laptop. They both behaved perfectly with Wheezy.
By default I boot into xdm and Openbox. This works perfectly, all the time.
After an upgrade to Jessie, I get the following problem on both computers.

In /etc/lilo.conf I have:
image=/boot/vmlinuz-3.16.0-4-amd64
label=Linux_console
read-only
initrd=/boot/initrd.img-3.16.0-4-amd64

image=/boot/vmlinuz-3.16.0-4-amd64
label=Linux_desktop
read-only
initrd=/boot/initrd.img-3.16.0-4-amd64
append=5

In /etc/inittab I have:
# The default runlevel.
id:2:initdefault:

I have removed the links in /etc/rc{2,3,4}.d to /etc/init.d/xdm.

This has always booted runlevel 2 OR 5 as selected in lilo.

Now after the upgrade to Jessie, regardless of the lilo selection, I get runlevel 5.

Please help me bring back this choice.

Looks like the upgrade installed systemd. inittab is not used and assume the default target is set to 5. The easiest fix would be to reinstall sysv. I have not played with lilo in a long time so maybe others know how to update it for systemd.

Thanks for the tip on systemd.

I have partially fixed the problem by doing a fresh install of Jessie.
By doing the install one step at a time I hope to learn about how systemd works.

Any tips on uptodate documentation as applied to Jessie?

Since fedora has had systemd longr than debian maybe you should checkout the fedora documentation.

I found the solution!
Because systemd sets the default runlevel to 5,
Lilo has to be given the line " append="2" ", after the stanza for runlevel 2.

Under "inittab" I have alway put the line " append="5", after the stanze for runlevel 5.

Congratulations! Glad you got it working.