I don’t really have advice, but I understand your feelings and would feel the same way. It sucks to feel left out, and I’m sure you would like to go too. I get having traditions, a trip to Disney PARIS seems to exceed a “tradition” IMO. And to exclude a SO from such a big trip (that you will probably never go on at another time) seems a bit much. I’m surprised your SO wouldn’t want you there- I couldn’t imagine my SO excluding me from any type of trip with a skid. 

If that's the way he wants it, then you know what, go out and have a nice time with your family and friends while they're away. and the next time you want to plan something with someone, like a sibling get away, or with some friends and it doesn't include your DH - don't feel the slightest bit guilty about it

This. Could  be a big RED flag.  Question is how do you handle this.  One, Insist on going with them.  Two, make plan for a trip Paris in three months. Three, break up over this.  

Dating for Two years is a good deal of time, there are marriage that don’t last two years.  He is not concerned on making thing equal.  You have to put up with SD but he does not see that as a problem.  He has to know you are going to make life hard for him after this 

this may not be the end of trips with SD 

I know you feel left out but he should have time with his daughter and you should have your alone time with him too, like your Vegas trips. Im sure you wouldn't want her tagging along on those trips.

I still take trips with my adult son and spend time with my adult boys without DH. I have a bond with these boys that he is not a part of as he came into our life when they were 20+ yrs old.

I do know the feeling though when him and his kids talk about things they used to do. They used to have pizza & movie night. They talk about the dog tjey had, the house they had with BM. It makes me sick cuz BM was involved. She is such a thorn in our side now, I cant imagine a time when he was her husband blah

This would be a deal-breaker for me. I agree with the poster above who said two years is a serious amount of time. At this point, I'd expect my relationship to move toward integration of family obligations, holiday traditions, birthday celebrations, etc. And it sounds like you do too. 

I don't think your BF is doing anything "wrong", I just don't believe that what he's doing is right for you and the kind of relationship YOU want to have. You see plenty of posters here are a-OK with his choice and tell you to go have fun by yourself... if you felt similarly, this tradition would not be a problem. But it seems that you want to be with someone who includes you and your BF is saying he's not going to include you -- he's going to keep you separate (smaller trips like Vegas). Not just separate, but in my opinion unequal. (Where do you live? Do you feel Paris is on the same playing field as Las Vegas? Because I don't and that's definitely influencing my opinion of the situation.)

I don't think he should have to change the tradition to accommodate you. I could see how that would create a number of problems with his daughter and between you and his daughter as well. But I also don't think you should have to miss out on a celebration every year because it's their "tradition" to be alone. In Paris this year, no less.

I am the last person to advocate leaving a relationship over a disagreement, but this doesn't seem like a disagreement. This seems like a fundamental misalignment of values and priorities, where neither one of you is wrong but your beliefs and ideals simply do not match. Is this really how you want to spend his birthday every year for the rest of your life? 

When I was with my ex, I would take my two adult boys out to dinner, just the three of us, once a month or so. I didn't invite ex, as it was just a catch up for myself and my boys. Though they did like ex and there were no issues, it would have been a different dynamic if he was present. We wouldn't have been able to talk as freely, and about particular subjects.

Ex understood this and didn't mind. Similarly, I encouraged him to spend time with his 2 older kids, without me present. Again, I had no issues with his older kids and we got along fine. Youngest SD was another matter altogether! 

In saying all that, I understand where you're coming from re the trip to Paris... that's quite a big thing and it's natural for you to feel "left out". 

As someone else said, focus on planning something nice for yourself to do while they are away. A weekend at a nice hotel with a girlfriend maybe?

And when your BF is back, tell him you hope he enjoyed his daughter's "coming of age and leaving home" trip (lol) and that you would love to plan an overseas trip for the two of you.