How to split the bill when dining out?

Tomorrow we're going out with DH's old boss and I'm feeling a bit nervous about how to pay for the meal. This is our first meal out with them, we only went to their home once (big celebration) and we never socialized with them before. Should we pay? Do we split the bill?

How do most people typically split the bill when they go out? I hate this scenario because there are so many different situations. We'll start with friends, typically we divvy it up our share and throw in money. Often times someone throws in extra, but no big deal. Or we sometimes ask for separate checks. I guess also depending the person, sometimes we just go back and forth, it seems to happen with our two best friends the most.

But how do you split a bill with coworkers? I've found that a lot of them like to just split the check equally which is difficult for me because I don't drink when out with others I work with. This means typically my share of the bill is substantially less than others, and I'm always bothered that I'm paying for someone else's beer. Sometimes I'll get a separte check and say I'm paying by credit cards. Or other times I'll just drop in enough cash to cover my meal + tip/tax. Is this wrong?

Finally I guess is family, do you pick up the bill or split it? I've found that we pick up the bill depending on the family member. We've started making "real" money so we've started paying for our parents. And unfortunately other family members are starting to expect the same as well. I find this a bit difficult because it's the two of us, but my sibs and their kids, so the balance is a bit disproportionate. Also I feel we're expected to treat because we make "good" money and have little responsiblities, which is true, but I'd love to save a bit more instead of blowing a lot on a dinner out.

Well since we're out to lunch tomorrow if I have a chance I'll try and update on the splitting the tab situation.