IMO, even with the commonly used house rule of granting a +3 to the skill checks from the SKILL FOCUS feat, it is still a weak feat.
Here's my new house rule:
SKILL FOCUS: You gain a +2 to all checks with the skill AND this skill is now always considered a Class Skill for you. You can take this feat multiple times, but each time you select a different skill.
Also, ALERTNESS could work similarly, but maybe be toned down for balance issues.
ALERTNESS: You gain a +1 to all Spot and Listen checks AND these skills are now always considered Class Skills for you.
Here's my new house rule:
SKILL FOCUS: You gain a +2 to all checks with the skill AND this skill is now always considered a Class Skill for you. You can take this feat multiple times, but each time you select a different skill.
Also, ALERTNESS could work similarly, but maybe be toned down for balance issues.
ALERTNESS: You gain a +1 to all Spot and Listen checks AND these skills are now always considered Class Skills for you.