Given how cheap everything in the Astra Militarum is these days, it seems eminently plausible, if not advisable, to field a full Brigade. You can do this pretty easily in 1500 points, and certainly easily in higher point levels.
By way of example:
HQ
Company Commander (Warlord)
Company Commander
Commissar
These two accompany all the infantry to kick out orders/keep them in line
Company Commander w/Powerfist
Rides in the Valkyrie with the Command Squads to try to keep them from melting their faces. Incidentally: holy crap are powerfists cheap these days!
Tank Commander in Executioner, Plasma Sponsons, Heavy Bolter
It's a real shame that the commander can't issue tank orders to himself. Honestly, this tank is probably overpriced for what it does, but I own one and I'll be damned if it's just going to sit on a shelf.
Troops
Infantry Squad w/Flamer
Infantry Squad w/Flamer
Infantry Squad w/Flamer
Infantry Squad w/Flamer
Infantry Squad w/Flamer
Infantry Squad w/Flamer
That's sixty dudes for short money. Throw around enough FR/SR orders and things will die. Or they'll die and you won't care--win/win!
Elites
5 Ratlings
Not sold on these little guys, but they're cheap and have some handy little abilities, so they're worth a shot. I might be better off with more heavy weapons, though.
3 Bullgryns w/Mauls, Slabshields
Countercharge unit. Their save with the shields is great and the mauls can put a big dent in a lot of units.
Command Squad w/4x Plasma Guns
Command Squad w/4x Plasma Guns
If I told you how much each of these squads cost, you might cry. Yes, they will be overcharging their plasma guns. With the commander nearby giving them orders, I expect they can get off a volley before their untimely demise. The only thing that matters is if they kill something worth more than they are. Given their cost (even with the commander), that shouldn't be hard.
Fast Attack
Scout Sentinel w/Missile Launcher
Scout Sentinel w/Missile Launcher
Scout Sentinel w/Missile Launcher
Cheap and versatile, can be used to block off sections of the board from those sneaky units that show up with a 9" bubble. Indeed, the entire army has such a large footprint, most armies will really struggle to put something in your backfield if you don't want it there.
Heavy Support
Leman Russ Punisher w/3x Heavy Bolters
My current vote for most cost-effective tank. Any support it receives from the Tank Commander makes it even better.
Lascannon Squad
Autocannon Squad
Heavy Weapon teams are crazy cheap, guys. Crazy, crazy cheap.
Flyers
Valkyrie w/Multilaser, Multirocket Pods, Door Hvy Bolters
Shuttles the Command Squads about, shoots things.
Totals
This comes to about 50 points over 1500, so I can see cutting the Ratlings and/or maybe the Commissar (if you need somebody to stick, you have 12 CP to do it with)
12 Command Points
22-drop Deployment
So, you will pretty much *always* be going second, but the number of guns you put on the board might counteract that liability.
The question sort of becomes "do you need 12 CP." I haven't really played or tested out enough 8th Edition to say as of yet, but it seems as though it might be really handy. The only problem comes from Matched Play, where you can only use each command ability once per turn (I feel like the command re-rolls should be immune to that rule, but whatever).
Thoughts?