Prepare the easy guacamole: Cut avocados in half and scoop out the avocado into a medium bowl. Mash the avocado with a fork. Stir in sour cream. Season to taste with salt and pepper, cayenne and a squeeze of lime juice.
Make the grilled cheese toasts: Preheat oven to broil and set rack in the middle of the oven. Place baguette slices on a baking sheet. Spread each slice lightly with butter (I use spreadable tub butter), and sprinkle with garlic salt. Broil the bread slices 1 to 2 minutes, just until beginning to crisp. Top the bread slices with shredded cheddar. Broil again until the cheese is melted and toasts are browned lightly on the edges (1 to 2 minutes). Remove from the oven.
Assemble the bruschetta: Place the grilled cheese toasts on a platter. Spread each toast with a generous smudge of guacamole, a few bacon pieces and tomatoes, and a garnish of cilantro or Italian parsley. Serve immediately with lime wedges added to the platter for optional squeezing.
Notes
I prefer to use center-cut bacon (and it's a bonus if you can find the Applewood Smoked variety).