Some good idea's there Gath I will throw a few of my own into the hat so to speak:
Guildleves
Solo SP/EXP from Leves would be king here. Leves should be adjusted so that the mobs give normal SP/EXP and then if you started or linked the Leve you will then get a lump sum at the end. The base lump sum will start with the Rank of the Leve so R20 Leve's give a lump sum of say for example 5,000 SP/EXP while R40 Leve could give 10,000 SP/EXP. From that base you add multipliers that can add or subtract from that total. Things like time taken, star ranking, your current rank, amount in party if not solo. These could add an extra 50% to the base if you do the Leve correctly and skilfully based on the parameters to take that total to 15,000 SP/EXP for a R40 Leve.
Now people might be sore that they can no longer get the great SP just by being in the Leve but these are designed for Solo really and also to be quick content for people without much time so your just going to have to let the Leve abandoning go. You can still link the Leve but you would not gain more SP in the way that we do now instead you would gain more by setting the Leve on a higher difficulty and it would be a smaller boost than what we are accustomed to. This would make Leves still a good option for a small Party but still not create the huge gap there is now between Party and Solo for Leves. Then there is GA also which can give a boost to the total as well, this is a great tool for Casual players as they will always have lots of it for that SP/EXP boost when doing Leve's allowing them to make good progress in the time they have.
Party Grind
I think you covered most of this already Gath but basically changes to Mob distribution, respawn time and removing the 10 Rank SP cap on Mobs. Also of course add SP/EXP chains into the mix to give that extra keep going incentive. There should be plenty of camps available for all leve ranges throughout the land with Coerthas and Mor Dhona being aimed at higher Ranks.
Dungeon Grind
Here I was thinking mobs within the Dungeon would grant there usual SP/EXP but the Bosses would have huge bonuses also if you manage to complete the Dungeon maybe one of the rewards could be an SP/EXP scroll to use on any class.
Quest Grind
This one is tricky as they could easily fall into the Leve category. I think it would take a long time to implement but a kind of flowing quest line could work with SP/EXP rewards upon completion of each stage. What I mean is the quests kind of follow each other on telling a story, so you are not repeating the same quests over and over again. As a basic example it could start with helping an NPC get an item, you do that quest complete. Then he asks you to deliver the item, you take it to new NPC quest complete. New NPC ask for your help with some dodo's that have been causing havoc in his lettuce patch. The quests keep building up and getting more challenging with NM/Boss fights further down the road telling a story all the way along.
Company Grind
This is what I would most be looking forward to if it is anything like Campaign from FFXI but brought up to date and with new idea's. I won't post all the idea's I had for this here though as it would be a rather long post and I have a thread for it located below:
http://forum.square-enix.com/ffxiv/t...at-do-you-want
If they could do anything in there I would be more than happy regardless of anything else they did with the game.