Random seeding + Double Elimination is the way to go. It's the only way to promote fair competition in an un-ranked tournament system in the most unbiased and professional way.
Whether or not people don't want to play against their friends shouldn't really be the primary concern. Fairness, professionalism, and objectivity should be.
Why Crew-based seeding & Round Robins are unnecessary and often biased
I am of the opinion that one should NEVER separate people by crews in double-elimination brackets OR in Round Robins. Manual placement of players by crews is purely subjective, and it allows people to choose who they're not going to play in the brackets until later. This is a one form of bracket fixing: trying to manipulate the brackets in such a way that is advantageous to players who belong to crews.
The competitive nature of double-elimination is such that it gives everyone a chance of advancing to a certain degree according to their skill level. The random aspect of it must be maintained in order for it to work. It is the most objective manner to carry out tournaments that I know of because of it.
In any bracket system, it is extremely important to note that players MUST NOT be allowed to look at the brackets beforehand!! I am aware of several cases where top-tier players in Illinois have actually made shady deals with each other in order to promote their advancement and cash returns.
For example, two friends (or crew-mates) are about to play each other in the winner's bracket, and they see who the loser plays next (in the loser's bracket). If one friend thinks they can beat that player that their friend cannot, he would simply agree to forfeit or throw the current match to his friend, get thrown into the loser's bracket, and play the next match. This is also considered conspiring to fix the brackets, and is penalized by disqualification in MLG.
Round Robins, regardless of whether you separate by crews or not, easily become biased due to one player's ability to directly affect another player's advancement through forfeits.
Stupid Fast-like-Tree rule is in place specifically for that reason.
For those of you who don't know this rule, it was invented at MELEE FC6 when FastLikeTree purposely lost to a friend (?) of his, which ended up ousting AOB from advancing.
The reason why this happened is because AOB and another player were about tied for advancing in wins/losses, and FastLikeTree was at the top of his pool. Fast-like-Tree could sacrifice one loss and still advance, and so when FastLikeTree played against his friend, he gave him the one win he needed (pretty much by throwing the match) to beat AOB's record and advance.
If you plan on spending the ghastly amount of time it takes to run Round Robins, make each player report their wins/losses to a designated scorekeeper (not a friend!), and KEEP PLAYER SCORES CONFIDENTIAL!!!
Bracket fixing is a serious problem among independently-run tournaments, and all efforts must be made to reduce such a form of cheating.
Again, more effort must be made to promote fairness, professionalism, and objectivity than promoting subjective, player-player relationships in tournament play.
P.S. Sorry BigC. I don't believe in crews holding any substance in competitive play.
P.P.S. TJ, stop forgetting that I exist in your shoutouts (it's annoying), and I'll wish you congratulations for your win over Eddie and taking 2nd place in singles.