940s are nice but they are barely bigger than a Mini-Grip.
If you like the Mini Griptilian but want something a bit bigger, the obvious choice is a Large Griptilian.
Also consider getting custom scales for your Mini-Grip, or for a Large Griptilian if you get one. The scales on the normal Grips are not terrible, but getting nice G10 (or CF, Ti etc...) scales totally transforms the knife into something much better.
You should also look at Ritter-Grips. They are a special version of the Griptilian that use M390 blades and a broader blade shape and are a perfect candidate for scale upgrades. A large RitterGrip (with or without custom scales) will offer you a larger version of the knife you already like, but with enough differences to make it distinct from what you already have.
If you want something different, not another Grip, look at the 710. It is the original Axis lock knife and to this day one of the best folding knives, period. It has a lot of blade for the handle, making it easy to carry but with the cutting edge length of much bigger, heavier knives. It is *THE* classic Benchmade. Depending on what you mean by "half an inch bigger", the 710 might be longer than you want, but it is worth looking at.
If you are a Benchmade fan, the 940 and 710 are both classics that you should at least consider owning, but if you get a 940 you will have two small knives, and it sounds like you want something bigger. So seriously consider the 710 and possibly even the slightly more expensive 710-1401. Also the Rift; it is about the same size as a Large Grip, but comes with G10 scales.
To be honest, while the 940 is "nicer" than the stock Mini-Grip, putting custom scales on a Mini-Grip (or better yet a Mini RitterGrip) you end up with something even better than a 940. I just like the dimensions and appearance of the Grip more than the 940, but that's just me.
If you end up with a Mini-Grip, 710, and an 940 as your first three Benchmades, you'll have a great start! Those are pretty much the 3 most popular Benchmades ever along with the Large Grip.