I was offered a ticket by someone at school but declined it because I didn't like Morrissey's mob at the time. I would love to be able to clip my 17 year old self around the ear and tell him "Stupid boy!"

Glasgow barrowlands early nineties... I had the flu...should have just gone and risked pneumonia..

Stackridge were also on the Wembley bill.

...at the Apollo in Glasgow, 1978 (?). Bought a ticket for The Clash instead on lack of funds grounds...

I had my ticket but was told that I had to work (trainee manager at Woolies - refusal wasn't an option in those days if you wanted to get on in the company), so I sold it to my brother's friend (face value). I don't wonder what I missed - I bloody know!
Needless to say, me and Woolies went our separate ways as climbing career ladders was not for me. (I also missed Leonard Skynrd at the Brighton Dome for the same reason).
Regrets? I've had a few...

Santana at the Birmingham Odeon - it was around the time of Love,Devotion and surrender which I didnt like. Apparently the show was a stormer and he played most of his Abraxas era 'hits'.

From more recently Stackridge (coincidence Beany) at Robin 2 last year - I only didnt go because I had been to far too many concerts in the same month. My brothers mate went and raved about it.

Manchester Free Trade Hall - 85/86'ish time.

Only seats left not even two together. Gig going friend & I decided not to buy and went for a pint instead.

I still remember turning around and walking out of the ticket office (the old Picadilly Box office for those in M'cr) thinking we had done the right thing.

25yrs later, I still scold myself for such foolish behaviour.

I had a ticket for the reformed Roxy at the Liverpool Summer Pops a couple of years ago, had it for months, couldn't wait but didn't make a note of the date anywhere.
Realised I'd missed it when I read the review in the next day's Echo. Despite having printed proof in front of me I still ran to the drawer upstairs to check the ticket somehow believing that the review was wrong and that the gig was NEXT week not this.
Strangely, it wasn't.
i believe the expression is Doh.
(what happened to that new Roxy album?)

played in Belfast in August 1994 in the Limelight, a tiny club venue. I am pretty sure it was the day after 'Grace' was released. I had bought the 'Live at Sin-e' CD on the back of a Rolling Stone review, and because it had a Van Morrison cover. I decided to give the gig a miss because ... well now I can't even remember why, but he was bound to be back.

He was on at The Garage in Islington, not my favourite venue. I decided I'd catch him next time he came around.

Not just a ticket but also a lift there and back from Lynn. Kick me someone please.

I had the dilemma as a 19 year old on whether to go to Live Aid as my mate had got 4 tickets or go and see Dire Straits at the Wembley Arena on the same night.

We chose Dire Straits on the basis that we would see most of Live Aid on TV and still get the live experience as well....wrong decision with hindsight!

We did get Sting onstahe during Money for Nothing but that was little concellation.

I was a pompous, self-important so and so at the age of 16. I constantly ridiculed my mother for her love of Bruce Springsteen: just awful, bombastic stadium rock, isn't it? I said. Anyway, she was going to see him at Wembley in 1988 and one of her friends pulled out. I can see her now standing in front of me, telling me that I might just enjoy it. He's the best performer you'll ever see live, she said. I'd revise my view of him, she said. Even if I didn't, what could I possibly have to lose?

As I said, I was an idiot at that age. Eight years later, my mum was dead, and I was fully aware that seeing Bruce Springsteen in concert is the kind of experience that every human being should have. I've seen him live 5 times now, and every time I wish she was there too. They say you shouldn't have regrets, but I do and this is one of the biggest.

Jesus and Mary Chain headlining over Blur, My Bloody Valentine and Dinosaur Jnr. Instead I went to see Soundgarden who were playing the same night.

I made very much the wrong decision (sigh)

had a free ticket. Quite liked Come As You Are but decided not to bother. Silly me.

a small club in Glasgow when Ten had just been released, it was on a work night so I decided no. Aerosmith c. Rocks at the Famous Glasgow Apollo™, it was raining very heavily and the phone lines were down so, I couldn't get in touch with my mate, stayed home. Blondie and Television at aforementioned ™ place, dunno what happened, Sunday night apathy took over I guess.
I also managed to miss The Sisters Of Mercy 3 times in their amphetamine filth days, how that happened is beyond me and something I still beat myself up over.