My folks are in their 50s. I am the Executor of Mom and Stepdad's wills if any should happen to both of them, so I have copies of their wills and other legal docs. I also know that Mom would like to have a Mass said in her honor and wishes to be buried at the Catholic cemetary (away from the highway since she hates noise

). Mom and Stepdad would want to be buried together. Since Mom collects angels, I told her I would have a nice angel etched/inscribed on her tombstone, which she thought would be very nice.
My Mom also has copies of our wills and other docs since Mom is the Executor of our estate if something should happen to both of us. Also, Mom and Stepdad would be the guardians of our children. They know that we are organ donors and would prefer to be cremated.
My Dad's brother was the Executor of his estate, last I heard, if anything should happen to him. Dad is also remarried and I assume that my brother and I would only get token amounts, if anything, if his wife should outlive him. I don't think that my Dad much cares what happens to him after he passes and honestly, whatever service/burial arrangements that Stepmom would prefer are fine with me, so long as I am invited.
I know my MIL and StepFIL don't have wills written up and I've discussed with MIL that they should. FIL and StepMIL do have wills.
Regarding how to discuss wills and burial arrangements, etc., I don't think there is any need to have a big family meeting. We have just let those around us know that they should have wills to make sure that their assets pass on to the people they wish to have them. We really don't care what we might get from the passing of our family members; afterall, it's not our money, and we would prefer to have our parents alive then to have their money.
So, I think that the important thing is to have a conversation about whether your parents have Wills, Health Care Powers of Attorney, and Living Wills and where they keep these documents in case you need them in the future. Also, a general discussion with Mom and Dad about funeral preferences is a good idea.
While we're at it, do you have a Will?