I travel EVERY week for work. I have seen it all when it comes to overhead bin space as I am sure most of my fellow bloggers have.

If your roller bag ONLY fits in sideways. Its too big. Check it. That is proper etiquette. An average of 5 rollerbags can generally fit into one bin wheels first. Two can only fit if sideways. This is rude.

If a jacket or purse is taking up bin space a flight attendant can ask whomever that purse/jacket belongs to store it under the seat. Will they? No. You can though. I've done it many times. "Excuse me, can you please place this under your seat so I don't have to check my bag?". If they say no, well I am sure you could think of something to say to make them feel 2 feet tall. Especially if you're sitting next to them. Purposely HOG that arm rest! If you are sitting behind them, set the worlds record for opening and closing your tray table!

Elite members board the plane first. So kiss those front bins goodbye if you aren't an elite passenger. I always recommend NOT picking front plane seats unless you are elite because elites will board ahead of you and GOODBYE bin space. Elites (like myself) are the worst people to fly with. We tend to be very demanding without patience because we fly so much.

I, personally, always check one bag and take a backpack on board and push it under my seat. I think everybody should respect that other passengers have stuff too.

I think the soloution to bag space is this..

If it doesn't fit in wheels first..it must be checked unless...
Luggage should take priority. I.E. Wheels first fit > sideways fit > coats/purses/etc.

Why they don't enforce this is beyond me. Flights get delayed b/c people are to busy threatening each other!