A) Character Party Outnumbered Two To One By Monster Crew
1) Linear style. The party goes in one direction on a predetermined route (there isn't really that much difference between 'down the meadows', 'up the meadows' and 'there and back again'), often guided by a character ref. The monster statters run ahead with the monster crew and throw encounters back at the party as they attempt to progress along this journey, until the Final Encounter where the monster statters can do something really cool because they have the whole monster crew back. This is the basic kind of linear, it works fantastically on Grantchester Meadows which is basically one long line anyway, and we know the most about running it.
2) 'Choice' style. Runs very much like a linear, except there is some focal point where the PCs have to make a decision which will change what the rest of the encounters are. Slightly awkward to manage the transition unless very well-supplied with monsters. This 'single choice' style probably emerges from the fact that Grantchester Meadows has precisely one place where a party can go in one of two directions rather than one of one directions.
3) 'Persistant World' style. We've only really successfully run these in places which are not Granchester Meadows (e.g. Royston Woods, Abington Scout Camp). You divide the monster crew into 'persistant' NPCs who get a good briefing and have a reason to stay in the area, and 'raiding' NPCs which go and do a certain thing and then report back to the OOC kit dump. Then you send out all your NPCs and hope that the 'raiding' NPCs actually come back at some point (but hopefully the 'persistant' NPCs will give the PCs enough to do that the relative infrequancy of 'new' NPCs compared to a standard linear won't matter). In general I hugely prefer this style of linear but I haven't been confident enough to try it in Grantchester Meadows yet because it benefits a lot from having a squarish area that has multiple routes between places and at least one landmark that can be approached on all sides.
B) Monster Crew Outnumbered Two To One By Character Party
This is the recently developed 'interactive in a field' style of linear popularised by the Kender Picnic and the Grand Tournament, both of which seemed to go reasonably well. The action takes place within one field, there are a couple of persistant NPCs keeping things going and a couple of Raiding NPCs that come in and out keeping things interesting, but most of the action is meant to be focussed around the interactions of the PCs with each other rather than with the NPCs / the environment.
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I'm sure there are plenty of other unexplored linear styles we haven't got to yet. Things I want to do:
1) Persistant World on the Meadows which goes beyond Interactive In A Field
2) Start At Both Ends (or Some Start In The Middle for a 'rescue the captured people' linear) - probably a pair of characters at each end unless the society grows a lot
3) Linear In A Field - the character party stay in one place and the monsters come to them, but there are no/few real persistant NPCs unlike Persistant World (Creed's Hill PBB was like this)
4) Bases - two antagonistic bases are set up, everyone is persistant (except maybe, like, two or three 'incidental' monsters to keep things moving) - a less ambitious version of this with much less NPC persistance was done at the 'rescue the peasants - oops, there's an undead Charridy eating you' linear
5) Environmental Hazards - there is at least one monster at all times in a position to spawn in and attack the party if they are not already under attack - I tried to do this on the Nightmare Bash but didn't have enough monsters to keep it up, I think it will have interesting interactions with armour repair and mana meditation if anyone can pull it off