There are some great suggestions already but will share my personal experience with a 6 month trip away from home.
I had to travel to a neighboring country and am halfway through my 6 month stint.
Since I had to go to work, court and classes I took my Phantom, a Burberry Buckleigh tote (which I only use when I have to carry my lappie, which is very rarely) and my Nightingale (works for every situation and doesn't attract a lot of attention). For my off-time, I wear a Fendilicious (which is a wallet on chain bag) and my Chanel 228 (great for sneaking a drink and chips into the movie theater - don't judge). Gosh, I also took a small clutch and envirosax bags. :shame: (Geez, I'm quite a bag lady).
I'll admit, its a lot of bags but oddly enough I rotate them during the course of the week, depending on my personal needs.
With that said, take the bags you love, use often and will make sense for where you will be. A tote is always useful, as is a small bag. I agree that you should wait to get to your destination before buying anything new as you may find something you love. And if you're a bag lady like me, then take what you need and enjoy your 6 months away.
Good luck!
I love your collection!!
I also have a Nightingale in blue and I love it so much but I am afraid that something will happen to it....

I am thinking about buying a Neverfull Azur or Monogram in the size MM since my GM is almost to big. And maybe a Mulberry Lily medium or a Gucci Disco bag.