How you setup VLANs depends entirely on what you are trying to accomplish, and what hardware is involved. Let me give my specific example. I have two RB750s that are both connected to a single HP 2610-48 managed switch. All 5 ports of each router are in use and are connected to the switch (router #1 connects to switch ports 1, 3, 5, 7, & 9, and switch #2 connects to switch ports 11, 13, 15, 17, & 19). The switch currently has 9 different VLANs in use. Router #2 has an internet port, and 4 separate LANs (using all 5 ports), but router #1 has an internet port and 5 separate LANs (requiring one more port than it has). I am using two VLANs on an 802.11q trunk between router #1 and the HP switch (because of the need for one more LAN than the router has available). I am not using any bridges. And yes, I could have put all the LANs (and even the internet port) all on the same physical port of the routers and used a bunch of VLANs on a single 802.11q trunk between each router and the HP switch. However I'm not short on ports on the switch, and I like to be able to see the blinking lights when troubleshooting! Remember that if you are using VLANs in the router, you need to have something at the other end of the 802.11q trunk that can split the trunk back out to the individual LANs (either another router, a managed switch, or in some cases a NIC in a computer can handle multiple VLANs on an 802.11q trunk).
Now for the DHCP part. Router #1 has 4 address pools and 4 DHCP servers. Each server uses the interface for that particular LAN - whether it's a VLAN or a physical interface. Similarly Router #2 has 2 address pools and 2 DHCP servers - each using the physical interface for that particular LAN.
RB750Gr3, RB750r2, CRS326-24G-2S (in SwitchOS), CSS326-24G-2S, CSS106-5G-1S, RB260GS
Not sure if I beat them in submission, or they beat me into submission