Many situations also start with someone becoming lost. Make sure your kit includes navigation. Staying found is big and if it turns into an E&E you really want to where you're going.

Edit:
After some thought, either of the Garmin Foretrex GPS receivers or the newer fenix™ GPS, all wrist-worn would work. I kinda like the fenix™ because it looks more like a standard digital watch. Unfortunately, the downside is that Foretrex units require batteries and the fenix™ requires a source to recharge.

If you want universal and light, you want knowledge and skill; they are more important than the widget-of-the-month.

Absolutely.

After that, focus first on things that are hard to improvise. My top three are a knife, ways to make a fire and a flashlight for the wilderness. For urban/suburban areas it's cash, a phone and transportation. Depending on your level of training, the laws where you will be, and the relative safety of the area, you might consider self-defense options.

Another way to look at it revolves around the rule of threes: You can survive three minutes without air, three hours without shelter, three days without water, and three weeks without food. The rule is hardly absolute but it gives you a framework for setting priorities.

Yes, I agree with this, mobile phone has GPS. I think some satellite phones have GPS too.

Yes, this is what I used:
Air - can be caused either by an injury (most likely) or a dangerous chemical gas (less likely unless it is smoke). Two options – get help or get out. Get help – signalling, get out – navigation and tools to make sure obstacles can be dealt with. I suspect that if you are injured, you will be lucky to press a button of a beacon or, if there are people around you, they can use your kit to provide first aid and call for help
Shelter – layering, but it needs to be compact
Water - it is heavy and there is little to improvise, you either need to carry it with yourself, or have a filter. If situation presses hard, then I will drink as clean water as I can get and then spend time in a hospital.
Food – I tried to check survival statistics about starvation and could not find it. I suspect that it is not that frequent in non-conflict areas. So, I feel snares, fishing kit etc are good for keeping you busy and additional building material, but that’s about it.
I am not discussing weapons because there is a higher chance police will stop and search me in any country I visit than actually end up in a situation when it becomes essential.

Whatever else you decide on do the five 'C''s first.