Ok web api routing fun.
my web api route config is below. the geocoding and info routes are performing great. And I'm confused why the search one is not following suite.
/*
    ==Geocoding Endpoints==
*/
config.Routes.MapHttpRoute(
    name: "v1_GeocodeApi",
    routeTemplate: "api/v{version}/{controller}/{street}/{zone}",
    defaults: new
    {
        action = "get",
        controller = "Geocode",
        version = "1"
    });
config.Routes.MapHttpRoute(
    name: "v1_GeocodeMultipleApi",
    routeTemplate: "api/v{version}/{controller}/multiple",
    defaults: new
    {
        action = "multiple",
        controller = "Geocode",
        version = "1"
    }); 
/*
    ==Search Endpoints==
*/
config.Routes.MapHttpRoute(
    name: "v1_SearchApi",
    routeTemplate: "api/v{version}/{controller}/{featureClass}/{returnValues}",
    defaults: new
    {
        action = "Get",
        controller = "Search",
        version = "1"
    });
/*
    ==Info Endpoints==
*/
config.Routes.MapHttpRoute(
    name: "v1_InfoApi",
    routeTemplate: "api/v{version}/{controller}/FeatureClassNames",
    defaults: new
    {
        action = "FeatureClassNames",
        controller = "Info",
        version = "1"
    });
}
so i want to have a url like http://webapi/api/v1/search/fc/rv. This url produces the below stack trace and resulting 404. I thought the convention was that if you had a controller with a get method it would be used by default. That seems to be what happens with the first geocoding route.
w3wp.exe Information: 0 : Request, Method=GET,
Url=http://webapi/api/v1/Search/fc/rv,
Message='http://webapi/api/v1/Search/fc/rv'
w3wp.exe Information: 0 : Message='Search',
Operation=RouteVersionedControllerSelector.SelectController w3wp.exe
Information: 0 :
Message='WebAPI.API.Controllers.API.Version1.SearchController',
Operation=DefaultHttpControllerActivator.Create w3wp.exe Information:
0 : Message='WebAPI.API.Controllers.API.Version1.SearchController',
Operation=HttpControllerDescriptor.CreateController w3wp.exe
Information: 0 : Message='Will use same 'JsonpMediaTypeFormatter'
formatter',
Operation=JsonpMediaTypeFormatter.GetPerRequestFormatterInstance
w3wp.exe Information: 0 : Message='Selected
formatter='JsonpMediaTypeFormatter', content-type='application/json;
charset=utf-8'', Operation=DefaultContentNegotiator.Negotiate w3wp.exe
Warning: 0 : Message='UserMessage='No HTTP resource was found that
matches the request URI
'http://webapi/api/v1/Search/fc/rv'.',
MessageDetail='No action was found on the controller 'Search' that
matches the request.'',
Operation=ApiControllerActionSelector.SelectAction, Status=404
(NotFound), Exception=System.Web.Http.HttpResponseException:
Processing of the HTTP request resulted in an exception. Please see
the HTTP response returned by the 'Response' property of this
exception for details.    at
System.Web.Http.Controllers.ApiControllerActionSelector.ActionSelectorCacheItem.SelectAction(HttpControllerContext
controllerContext)    at
System.Web.Http.Tracing.Tracers.HttpActionSelectorTracer.<>c__DisplayClass2.<System.Web.Http.Controllers.IHttpActionSelector.SelectAction>b__0()    at
System.Web.Http.Tracing.ITraceWriterExtensions.TraceBeginEnd(ITraceWriter
traceWriter, HttpRequestMessage request, String category, TraceLevel
level, String operatorName, String operationName, Action`1 beginTrace,
Action execute, Action`1 endTrace, Action`1 errorTrace) w3wp.exe
Warning: 0 : Message='UserMessage='No HTTP resource was found that
matches the request URI
'http://webapi/api/v1/Search/fc/rv'.',
MessageDetail='No action was found on the controller 'Search' that
matches the request.'', Operation=SearchController.ExecuteAsync,
Status=404 (NotFound),
Exception=System.Web.Http.HttpResponseException: Processing of the
HTTP request resulted in an exception. Please see the HTTP response
returned by the 'Response' property of this exception for details.   
at
System.Web.Http.Controllers.ApiControllerActionSelector.ActionSelectorCacheItem.SelectAction(HttpControllerContext
controllerContext)    at
System.Web.Http.Tracing.Tracers.HttpActionSelectorTracer.<>c__DisplayClass2.<System.Web.Http.Controllers.IHttpActionSelector.SelectAction>b__0()    at
System.Web.Http.Tracing.ITraceWriterExtensions.TraceBeginEnd(ITraceWriter
traceWriter, HttpRequestMessage request, String category, TraceLevel
level, String operatorName, String operationName, Action`1 beginTrace,
Action execute, Action`1 endTrace, Action`1 errorTrace)    at
System.Web.Http.Tracing.Tracers.HttpActionSelectorTracer.System.Web.Http.Controllers.IHttpActionSelector.SelectAction(HttpControllerContext
controllerContext)    at
System.Web.Http.ApiController.ExecuteAsync(HttpControllerContext
controllerContext, CancellationToken cancellationToken)    at
System.Web.Http.Tracing.Tracers.HttpControllerTracer.<>c__DisplayClass4.<System.Web.Http.Controllers.IHttpController.ExecuteAsync>b__0()
at
System.Web.Http.Tracing.ITraceWriterExtensions.TraceBeginEndAsync[TResult](ITraceWriter
traceWriter, HttpRequestMessage request, String category, TraceLevel
level, String operatorName, String operationName, Action`1 beginTrace,
Func`1 execute, Action`2 endTrace, Action`1 errorTrace) w3wp.exe
Information: 0 : Response, Status=404 (NotFound), Method=GET,
Url=http://webapi/api/v1/Search/fc/rv,
Message='Content-type='application/json; charset=utf-8',
content-length=unknown'
Now if I were to make another route more similar to the second geocoding route with the /multiple making the route template api/v{version}/{controller}/**for**/{featureClass}/{returnValues} the routing works and all is happy. 
The controller signature is
public class SearchController : ApiController
{
    [HttpGet]
    public async Task<HttpResponseMessage> Get(string featureClass, string returnValues, [FromUri] SearchOptions options)
    {
        // ...
    }
}
My hunch is that the async Task part is throwing it off somehow with the default get binding but that doesn't make sense since it works with the modified route.