Note that the complementary bridge will short out the power supply during the time the gate voltage is transitioning. If rise/fall time is quick (using a gate driver chip is a good idea), this can be handled with some supply inductance and damping (no, you DON'T want as low a supply impedance as possible!). If transition time is slow (some transistors and resistors?), you'll have little choice but to use series resistance in the supply, which will impair efficiency driving whatever the load is.
The all-N-channel case is perfectly acceptable, as long as your "high side" gate drive voltage is above the supply. This is usually provided by a bootstrap gate driver, like HIP2101.
The gates can also be driven together as shown, but you are limited on supply voltage: in order to fully turn on the high side transistors, you need Vgs at least 5V, which means Vg will be 5V above the supply. But the low side transistor will have Vgs(max) rated for 20 or 30V, so your supply can't be more than 25 or 30V, worst case. For this reason, such a configuration is useful only rarely, and at that, usually as a cost-cutting measure.
Tim