I definitely recommend that you vacation with your husband without your baby! The quality of your relationship with your husband is as important for her well being as anything else is and is in fact more important than many things. So, go knowing that you are not only doing this for your husband and your relationship but also for your daughter.
She will be fine! She will be with her capable grandparents who love her and with whom she is comfortable.
You could get her used to staying overnight, you used to being away from her overnight and also begin finding ways to feel connected in your marriage by having a date night once a every week or two and leaving her with her grandparents.
Vacationing together without your daughter is very much worth it. Think positively about it. Instead of questioning it look forward to being together. Start talking about it and making plans. That in its self may help your relationship.
If you don't find a way to resolve your relationship issues they will grow and have the possibility of disrupting your marriage. Do you want that? You are fortunate to have a husband who understood and agreed to wait until now for the vacation. If I were him I would not continue with this amount of patience for long.
Your relationship with your husband is just as important as your relationship with your daughter. By continuing to put off the vacation you are giving him an unspoken message that she is more important than he is. If he were to begin to feel like "second fiddle" that would also damage your daughter.
Your daughter will be just fine with her grandparents. I know it's difficult to let go of our children but now is the time to begin. At 2 she is beginning to learn that she is separate from you and is beginning to want more independence. This is a normal step in that process. Prepare her and yourself for it.