You may be able to accumulate enough miles for RT award travel for 1 or 2 passengers, especially if all 5 of you can qualify for and received bonuses for new credit cards. Award seats should be easier to book for May than they would be for June or July. It's hard to advise further without the information requested by aeneas3, but there are two things that can be noted at this point.

1. AA and UA offer OW from NA to Europe for 30k miles. DL and US charge the same for OW as for RT (60k). This policy allows for much greater flexibility in using miles on AA and UA, a point that may be especially important in your case since you may wish to draw on 5 separate accounts. (An example: If you and your wife each have 30k miles with AA or UA, you can obtain 2 OW tickets for the same person and buy a ticket for the other one. If you and your wife each have 30k miles on DL or US, you don't have enough to use them for a flight to Europe.)

2. Award availability is likely to be greater on UA (together with its partners) than on other airlines. Much depends on where you wish to depart from, but in general terms UA could be your best choice.