My Dh travels a lot. It may be a little different from other people here because his trips, while still annoying to him, are not terribly stressful (perhaps he would disagree). They involve meetings and conferences during the day and going out to dinner at night, with generally a good number of free hours during the day. I don't know, but I don't think of this as really the same kind of stress as being home alone with an inconsolable 3yr old ("I don't want you I want daddy. I wish I had no mommy and two daddies") who just-wants-her-dad, especially while pregnant.
So when my DH comes home, he basically takes over.
That first night we usually go through the bedtime routine together. We eat together, play together, have bathtime, even put her to bed together. Usually by the time morning rolls around she has warmed up to him (sometimes even before morning she sometimes sneaks into his side of the bed just to make sure he's still there). The next day (he usually gets back on a Friday) they spend the whole day together, usually out of the house, which lets me get my head back together, and by the end of the weekedn we are back to normal.
It is hard for all involved and I know my DH misses our DD a lot on these trips (but then again I know he chooses to go to a lot of them to advance his career even when others could be going without him -- and that's something that is important to him and I have accepted it). It is hard for dd, but she has gotten used to it and we talk about him a lot when he's not here ("I miss daddy, don't you?" "Let's call daddy" "What do you think daddy is doing right now?" "We'll have to tell daddy about this when he comes back" etc.) but I think we have gotten used to it.
But I wonder how it is all going to work once the twins are born. I'm sure I will become a much less tolerant mama.