Having played a few city fights I have the following advice. Stormies rule! take flamers, a warlock with enhance, and they are the meanest unit on the board. With fleet of foot they can get through the kill zones PDQ, The extra attacl plus flamers if they dont use the attack, plasma grenades to even up the combat, hay wire grenades for armor killing, I just cant say enough good stuff about storm guardians. Warp spiders are good, because they do not take difficult terrain tests, and thier S6 weapon will kill a lot of armor. The exarch with blades surprise attack and withdraw will earn the points back in one combat. Jet bikes are very usefull. The 6" extra move allows you to get out of sight and into cover. For Falcons and vypers the CTM will be worth the points, just not getting hit is better than a holo field. Scorpians are an excellent troop choice, as are banshees, you get everyones full attacks if they are in 6" of the combat. D-cannon with thier dont need line of sight will rock supported by a squad of defenders a battery of 3 D-cannon will hold a whole quarter. Tactic is to move deliberatly, clear out a quarter at a time, usually owning two quarters and contesting the others will win you the game. Some scenarios are different so play to objectives, but dont forget those quarters.