For the most part we play 3025 era games and try to keep them fairly short (anywhere from 2-6 hours). So from this end we play with anywhere from 2-4 mechs each with a larger game typically consisting of a full weight lance and then a "scout lance" consisting of 2 mechs. Usually 3-5 players. Sometimes we split up in teams and do more of an objective based strategy but its mostly just a deathmatch. Other times we will play a free for all type match which gets really interesting. More mechs = more mapsheets. So a 4 player (2 vs 2) game with two mechs each would take place on 4 mapsheets and larger games are usually played on 6 mapsheets. The bigger fields allow for more movement and positioning. Which is a lot of fun in lance on lance fights, especially when scouts are involved.
Forces are usually mech only although we will play with vehicles from time to time. Instead of looking heavily at BV usually its something like okay each player gets to choose 1 heavy and 1 medium each. Or if its a lance then we'll set anywhere from a 200 to a 240 ton cap for 4 mechs. If we are playing a BV game its usually at the lance level where players can run their custom lances and then BV is usually capped out at ~4500. We have found this lets you run a good mix of units and the typical 4k really min / maxes your forces.
From that standpoint I usually field a ranged heavy or low end 4/6 assault as the bruiser / tank of the unit. Orion, Warhammer, Marauder, Zeus, Battlemaster, etc. Then round the lance out with a 4G Hunchback (makes games shorter

) a cheap scout / backstabber mech (like a Locust) and finish off the lance with a solid LRM fire support mech. This is the mech that gets downgraded or upgraded to meet the game requirements. If I have to stay at 4K BV or a 200 ton game I'll run a Whitworth or Trebuchet respectively, but if I can bring the lance up to 4500BV or a 220 ton cap then It will be a Catapult or heavier fire support unit that can chuck out more LRMs. We'll play a host of weights and other things but a typical game I usually run something along these lines.
Playstyle is simple, Heavy mech (Like my Orion) holds the line and dishes out firepower while soaking up damage. Between the longer ranged weapons and the Missile boats LRMs, this provides good cover while my Hunchback 4G gets in close with the AC/20 and picks off units that got caught in a crappy location due to initiative rolls. My scout either spots for indirect fire, gets a good position for a backstab against a slower unit, or runs interference as a screening unit for enemy fast movers that try to get in behind my guys.