Anyhow, having learnt a few things, I've designed two lists. The first one was with some help from Mal (always nice to have your opponent help out with stuff like this). It's a Tervigon based list, and I've got Warriors in at the time being. It looks like this:
19 Termagants
Tervigon
6 Shrike w/ bonesword and whip
6 Tunnelling Rippers w/spinefists
6 Warriors, one w/ venom cannon, the rest with deathspitters
Tyranid Prime w/regeneration
3 units of 2 Hive Guard
20 Hormogaunts
8 Genestealers
I've only just discovered that Toxin Sacs will give a lot of my figures re-rolls on the damage, so I might be dropping a few bits here and there to make room for them. The idea is to have the Tervigon pump out the gants, the Shrike to fly over and tear shreds out of the enemy, the Rippers to deep strike in, whilst everything else slowly advances forwards - probably using the gants as cover. The Hive Guard, all three units, will form my 'Circle of Death' (I take great pleasure in swinging my arms back and forth to make sure we all know where that circle starts and ends.)
The biggest joy with this list is that I get to build myself a Tyranid Prime. He'll be made by doing a Gattaca on his legs (that is, break them in two places at the joints, drill and pin them by about 1cm and then epoxy the gap), building the whip out of epoxy, the sword out of plasticard, bunging a Mawloc or Carnifex tail tip on the end of his and using a Carinfex's head, trimmed down at the neck, instead of the normal Tyranid head. I worry that the head might be outrageously big, but we'll see next week when I get a chance to convert it (and have a 'take two' with my picture taking.)
The second list I haven't tried yet. It's a fast attack list:
Hive Tyrant with wings and Hive Commander
3 Hive Guard
2 units of 6 Tyranid Shrike with double boneswords
25 Gargoyles
1 unit of 20 Hormogaunts w/ adrenal glands and toxin sacs
1 unit of 19 Hormogaunts w/ adrenal glands and toxin sacs
18 Terrmagants
The plan is to have the gants in reserve, ready to take a back seated objective. In a Kill Point mission I'll probably just send them on in, hoping that the enemy will have more worrying targets to shoot. The gargoyles will take front as a shield wall, backed up immediately by the Shrike, the Tyrant and the Hormogaunts, all of which should be able to keep up with the 13-18" move of the Gargoyles. I'll, obviously, leave the Hive Guard somewhere safe (hopefully) to crack open some tanks so my forces can tear them to shreds. Clearly, once the army meets the enemy the idea is to just lay on in and tear seven shades of shit out of them. Again, with this list I'm thinking of toying with it further - I'm very much in two minds about what to do with the Shrikes, and whether to take boneswords or a whip and sword. I'll see how they get on. In any case, I've not bought any gargoyles so will have to substitute gants or stealers or something in their place to see how they do before shelling out a gazillion pound on them.