I'm walking around manhattan, how far am I from my hotel?
J, 17 characters
2*|+/0j1^'urdl'i.

Uses the fact, that the powers of j represent the proper directions.

'urdl'i. take string and calculate indices (0 for 'u', 1 for 'r', ...)
0j1^ transforms into the direction in the complex plane using the corresponding power of j.
+/ sums up the single steps
2*| two times the modulus

Example:
&gt; 2*|+/0j1^'urdl'i.'uuuudrrrl'
7.2111