|Douglas Muir 406|
Personally, I find Toughness, and the +2 to two skills feats to be very weak. Skill Focus not only seems weak to me, but is also used as a tax, nonsensically for Eldritch Heritage among others.
Toughness: If you're elf wizard with an 8 Con, Toughness increases your hp/level by almost 40%. As a practical matter, Toughness makes Con-dumping builds possible -- maybe not a great idea, but possible.
I've also seen it played the other way: a guy who played a barbarian who decided to just get as many hp as possible. Adding Toughness didn't make that much of a difference in practical terms (18 hp at first level instead of 17 is a pretty small marginal increase) but it was thematic and flavorful. Again, sometimes that counts for more than game utility.
Skill feats: These get underused, but some of them are actually pretty fantastic. Getting skills like Bluff, Intimidate and Diplomacy into the stratosphere can deliver some astonishing in-game effects; you can instantly turn hostile creatures neutral, get information, deliver mass debuffs, and warp the minds of enemies into believing all sorts of nonsense. Being able to hit high DCs on these is really useful, and these feats are how you do it. And then of course there's Perception. It's the most useful skill in the game, used again and again to detect enemies, find traps, and locate treasure. Anything that raises it is good, good, good.
If you're playing a mounted character, better Ride can save your life. If you're a rogue, anything that increases your Stealth, same same. If you're a highly mobile melee type, raising Acrobatics is going to save you from a lot of AoOs. If you're a party face, you have every reason to want Diplomacy and Sense Motive pumped up. And so on, and so on.
Now, all skills are not created equal; you're not going to see a lot of people investing in Skill Focus: Swim. But you can do a lot of good, fun and interesting things with the skill-boosting feats.