First of all: there is a new DA codex coming out. Check out the rumours about what changes. There is alot of info on the warseer forums, for example. You don't want to spend a lot of time planning and modelling only to find out that your units are illegal, or less useful.
I haven't played SM-type armies (yet), but have played against them alot. The old meta was troops in transports, and even if the hull point system have made vehicles a little more vulnerable, transports are still a must have. Rhinos are cheap (pointswise), and give your units mucgh needed mobility and protection. I would plan for all important units not equipped with heavy weapons to have transports. Close combat oriented units will do better with assault vehicles, so they can storm out of their protecting transport and assault the enemy. DA have access to Land raiders, so I would get one of those, if I had say terminators.
There are also some new flyers, some of which can be used as transports, but I don't know which ones DA can use...
The trademark unit for DA is of course the bikers. DA Biker squads has access to special weapons, so a couple of specialised biker squads (say one with flamers, and one with meltas or plasmas) is probably good. Remember though that bikers, to the contrary of what many believe, are surprisingly flimsy, mostly because of their low head count, so you probably want to include a couple of extra bikers in each squad.
Land speeders are another iconic DA unit. They can be quite expensive if you kit them excessively, but the TYphoon type speeder used to be very popular. They have only two hull points though, so they will die easily if you let the opponent shoot at them.