There's a Warp Brothers remix of Free & Easy? WHERE?

Unless you meant "still alone", which I LOVE, and totally agree with.

I find most of ayu's Original songs aren't that danceable. Obviously she has a ton of remixes to go through, but there are a few that come to mind you can try:

GAME X YOJI (ayu-mi-x 6 SILVER)
still alone "Wrap Brothers Single Mix" (ayu-mi-x IV)
SEASONS "H-H remix" (NEVER EVER single) - this is the remix that plays right before the encore in ayu's concerts (with the dancing A symbol).
Whatever (Ferry System F' Corsten Vocal Edit Mix) (ayu-mi-x II version US+EU)

Hmmm... Some japanese tracks I would put on a dancefloor-focused playlist

Ayu:
Sexy little things, Ladies night, Sparkle, Shake it, Wake me up, rollin, Connected, Startin', Lady Dynamite, Nanana, Party queen, Naturally.

Hikki:
Movin' on without you, Traveling, This is love, Celebrate, Beautiful world, Goodbye happiness.

Koda:
But, Shake it up, Real emotion, Hot Stuff, Taboo, Pop diva.

Namie:
What a feelin, Sexy Girl, Wowa, Want me want me, Break it, Hide & seek, Naked, Rock u, Make it happen, Hot girls, Body feels exit, Come, Speed star, Put em up.

BoA:
Dakishimeru, Bad Drive, Lose your mind.

I think you may go with Don't Wanna Cry by Namie Amuro but the lyrics ain't right for a wedding haha! You may also wanna make decision on sth I got here: ROCK U by Ravex ft. Namie Amuro, Say The Word/Violet Sauce by Namie, Hurricane Venus by BoA, Joyful/V.I.P by Koda Kumi, July 1st/Lady Dynamite by Ayu (try remix track cuz I don't listen much to remixes), Peach by Otsuka Ai (a little kiddy and youngful hehe), Rakuen by Do as Infinity.

HAHAH! Wow, thanks for catching me! I was thinking of the single where that remix is found bwahaha. Love the "still alone" remix, too good omg

If you want come club remix music from Namie, you can always use the Uncontrolled Special non-stop remix

https://soundcloud.com/namie-amuro-r...n-stop-special

STEP you, Sparkle, Greatful days, Fly high and Wake me up imo

What about Key ~eternal tie ver.~, I believe I read somewhere that she specifically made that song to be played at weddings.

Ayumi: Shake It♥♥♥♥♥♥♥♥ Lady Dynamite, SLT, Startin'
Kuu: UNIVERSE!! ( I LOVE THIS)
Namie: Rock U
:love:love:love

Maybe I'm late but I'd like to suggest, at least for the romantic part:

ai ga mieta yo - Rina Aiuchi (as far as I know, she wrote this song for the wedding of a friend of her, so it would work)
pink baby's breath - Rina Aiuchi (it is a really sweet song I'm in love with...)
CAN YOU CELEBRATE? - Namie Amuro
Key ~eternal tie ver.~ - ayumi hamasaki
Virgin Road - ayumi hamasaki