Can I print my e-tickets later?

If you look into it julie you may find that round trip tickets are much less expensive then one way. When I flew on my visa it was $1200 for one way but only $650 for round trip...go figure.

It's not really an issue with checking in or anything. If you have a child under 2 are you buying them a seat or are they going as a lap child? My experience is that when my daughter flew as a lap child we always had to check in at the desk rather than self service and we prefer it that way, I'd rather have someone else who knows what they're doing rather than fumble my way through the self service check in.

Yeah, often you can find round trips cheaper than one way. I've just done a search on Kayak for round trip tickets to Edinburgh from Oklahoma (where your profile says you are) and it's coming up at about £600 per person for the cheapest seats, which is £3,000 for 5 tickets. That's $4,600 in US dollars - almost $1,000 cheaper than the one-way tickets you found (I think that's the adult ticket price, so you might get a cheaper fare for the kids if they are young enough) .

Checking in at the desk is no issue at all...certainly nothing to determine whether or not you buy a round-trip or one-way ticket.  Personally, I'm with WebyJ in the fact that I like checking in with an actual person.  Keep in mind that there are several issues that could make you unable to check in at the kiosk (I remember once the scanner wouldn't read my daughter's passport for some reason so I had to go to the desk so they could manually enter in her passport number for check-in) so don't assume you'll always be able to do it that way anyhow.

Check the prices though.  I know usually round trip tickets can be cheaper (or equal to) the price of one-way tickets but when I moved to the UK, I was able to find one-way tickets that were almost half the price of round trip through www.atiflights.com (round trip tickets were around $700 each and I ended up getting two one-way tickets for $800ish).  There were quite a few other people on this forum who also found dirt cheap one-way tickets from that same site...so it's worth searching around if you'd like to save a bit of money.