Crumbs

Name: Crumbs Bake Shop

Neighborhood: Loop

Address: 134 N LaSalle Street

Map (link above): red dotted markers

Nearest El Transit Locations: 

Clark/Lake station Blue, Brown, Green, Orange, Pink, Purple lines

Washington Blue line

Washington/Wells Brown, Orange, Pink, Purple lines

Hours: 

Mon - Fri 7am - 7pm

Other Chicago Locations:

West Madison, 303 W Madison

River North, 346 N Clark

South Clark, 42 S Clark

Bake On-Site: No (have a distribution center in Chicagoland area)

Individual Cupcake Prices: $4.50 ("Signature" size) and $3 ("Classic" size)

Boxing/Packaging: Fitted Clam Shell
What makes this bakery special:

They have two cupcake sizes available for single purchase: Signature (all varieties available) and Classic (chocolate and vanilla). Their Signature size cupcakes are huge, and famous for it.

Cupcakes Purchased and Reviewed: 

Milkshake Cupcake

Cake: Marble (Chocolate and Vanilla Swirl)

with Chocolate and Vanilla Swirled Cream Cheese and Cream Cheese Filling

Appearance: 3

Size: X-Large

Vanilla/Vanilla (right) and Milkshake cupcake (left)

Bite #: 7

Moisture: 3
Price: $4.50 (Signature)

Vanilla/Vanilla
Cake: Vanilla
with Vanilla Cream Cheese
Appearance: 1
Size: X-Large
Bite #: 7
Moisture: 2
Price: $4.50 (Signature)

Additional Notes:
These cupcakes are huge! I mean like solid cake-y softballs. For some, that may be something attractive of Crumbs, but personally I like to enjoy my cupcakes as a snack or dessert, in one sitting, instead of as a meal themselves.
The cream cheese filling of the Milkshake cupcake was strange and unexpected with an almost banana or malty flavor to it. The cake was rich and super moist,  and the vanilla swirl portion complimented the chocolate swirl portion in harmony.
The vanilla cupcake was moist, but seemed dry to the taste. The frosting was grainy (I mean, it's just sugar granules) and left a unique coating in my mouth. Overall, I liked the vanilla in the Milkshake marble cake much better.
The frosting-to-cake ratio was smaller than expected for such a large cupcake (which in my case was kind of nice because I prefer a small amount of frosting with cake anyway).
Cupcake selection is very diverse.
Quick service.
Set up for a quick drop in or you can eat at one of the many sizable indoor tables.

Sugar Bliss

Name: Sugar Bliss Cake Boutique 

Neighborhood: Loop
Address: 115 N. Wabash

Map (link above): bright purple dotted markers

Nearest El Transit Locations: 

Randolph/Wabash station Brown, Pink, Orange, Green, Purple lines

Lake station Red line

Washington station Blue line

Hours: 

Monday - Friday: 8 am - 7 pm

Saturday: 9 am - 6 pm

Sunday: 10 am - 5 pm

Other Chicago Location:

River North, 509 N. Orleans (updated 4/27/13)

Bake On-Site: Yes

Individual Cupcake Prices: $3.50 each (regular size) and $1.50 each (mini size)

Boxing/Packaging: Deep, secure box with inserts

What makes this bakery special:

Cupcakes are available in two individual-portion sizes, mini and regular, both available for individual sale. Most regular-sized flavors are available in mini size. Score!
They also offer monthly Cupcake and Wine Tastings, where ticket holders get six mini cupcakes paired with wine. A portion of the proceeds goes to a different charity/organization each month!

Cupcakes Purchased and Reviewed:

Chocolate Peppermint

Vanilla/Vanilla (Left) and Chocolate Peppermint (Right)

Cake: Dark chocolate 

with Chocolate Peppermint Buttercream

Size: Average
Bite #: 3

Appearance: 3

Moisture: 3
Price: $3.50 (regular size)

Regular sized cupcake options: top and middle sections
Mini sized cupcake options: middle and lower sections

Vanilla/Vanilla 

Cake: Madagascar Bourbon Vanilla
with Vanilla Buttercream
Size: Average
Bite #: 3
Appearance: 3
Moisture: 2
Price: $3.50 (regular size)

Additional Notes:

Buttercream on both cupcakes was airy, very sugary, slightly grainy but still smooth.
The peppermint buttercream had a pronounced mint flavor but it wasn't overpowering. The chocolate cake was very light and fluffy.
The vanilla cupcake was slightly dry but not unbearable. The frosting is what made this cupcake, even if it is a little too sugary for my personal liking. 

Small shop with some seating by the street-view window but more set up for a quick stop in. 

Quick service.

Nice full display of cupcakes and multiple options.
The door in the background of the above photo leads into the kitchen where the cupcakes are baked fresh. It's cool to be able to see that for yourself as a cupcake enthusiast (and general consumer!). 

Easy to find and close to multiple El trains.