I'm blown away by not a single comment on adding a wide angle lens 14-24mm or the 16-35mm VR to the mix. Or even adding a 50mm for receptions. You would get many many years of service from those and much better bang for your buck with those.
SB-800 or SB-900 for some CLS work. Qflash is a great unit but the SB-900 or even SB-700 maybe worth it to you for the more advanced features. Maybe even other lighting or a background system?
Unless you do allot of video your macbook is just fine for a couple more years. I have forgone an upgrade this year and just bought better backup drives. Imac - I do not like the glossy screens. If you are going to upgrade, Mac Mini + monitor - computer last 3-4 years - monitors can get you 6. I see all-in-ones as a waste of money. They look cool though.
2nd Body - Probably not the best time to be buying a higher end body. I'd wait until a new D800 or D4 comes out then decide if you need a back-up or a new body and use your D700 as a back up.
I like the comments on training and education. You have a great set-up now and if it is working for you the most bang for your buck as you well know, is education.