I will never fly JetBlue again. I recently booked a trip with them--they had a great rate, which saved me about $80 RT over Southwest. I was attending a memorial service and had to make it a quick trip.
My flight down was wonderful and I was very impressed. I was beginning to think I'd fly JB more often.
Then...I went to sign in for my flight home and got a message telling me I couldn't check in online and to see a service agent at the airport. I checked my phone, as I'd signed up for their service alerting me to changes/cancellations (and got an email confirming I was on the alert list). There was no notification on my phone. I decided to call (thank goodness) and found out my flight had been cancelled! There wasn't another flight until the next day, they couldn't guarantee they could get me on it as everyone else on my flight had to be accommodated as well, and they told me they don't book on other airlines. I couldn't take the chance I wouldn't get home the next day, plus it would have meant another night's hotel charge and airport parking fee. They offered to fly me to San Francisco (I was parked at Sacramento airport and live 2 hrs north of that) or refund my one-way fare. I opted to be reimbursed for the flight home but it cost me $250 over what was refunded for the 2 of us to rebook a flight on SW that day.
I called over and over and over. I spoke to supervisors, I emailed, I wrote snail-mail. They are within their legal rights to leave you stranded like that. I *could* have waited until the next day and *maybe* gotten home, but I still would've been out the hotel and parking money.
As you said, OP, the worst part was the fact that I wasn't even notified. If I had waited until time to go to the airport to check in, I would have been stuck, as SW doesn't fly out of LGB.
I've had numerous cancellations and flight changes, but never have I received the horrendous customer service that JetBlue dished out. The final blow was a supervisor telling me it was my fault because I should have purchased
travel insurance.
So...JetBlue, never again. I will stick with SW even if it costs me a little more. It doesn't save you anything (and may cost you a lot) if your flight is cancelled--and apparently it isn't an unusual occurrence with JB. With only a couple of flights a day between LGB and SMF, it isn't worth the risk to me.
This is the hard part about customer service. People assume they can overlook communications on the part of the business, and as you learned, you really ought to read all of their emails, unless it's obvious advertising spam, like Fly to Zimbabwe Today Only ! $23 Round Trip! I mean, we've all read email enough to see what's advertising at first glance. Anything that does not fall into advertising should be opened and read. Espeically with the investment that a flight is, it's worth your full attention.
What you experienced isn't unusual, not for JetBlue and not for other airlines. Perhaps you could change your expectations to help with the disappointment? Sorry you were bugged by this!
I object to blaming the customer for the deficits of the company. The OP said that the information was in her itinerary without a specific notification of flight changes. Airlines owe it to you to let you know when they've made a change in your itinerary. In my case, I received no notification at all that my JB flight was cancelled and there wasn't another one. I fly often and this was the only time I've ever had a change or cancellation without notice or any attempt at compensation. I don't think people should have to change their expectations of being treated respectfully.
I refuse to fly Frontier Airlines due the same issues OP. 
I used it on this November's flights from SLC to LGB. 
DH was on a flight from Laguardia 
to SLC. Cutting to the chase, the ended up sitting on the runway sans info, food, and water for over 4 hours. After 2 calls and a scathing email, from me, they gave him a $300 credit. The irony is he refuses to fly them again. It's a transferable credit though; maybe I should eBay it. 
