partial class Examples
{
  public static Result SetActiveView(RhinoDoc doc)
  {
    // view and view names
    var active_view_name = doc.Views.ActiveView.ActiveViewport.Name;

    var non_active_views =
      doc.Views
      .Where(v => v.ActiveViewport.Name != active_view_name)
      .ToDictionary(v => v.ActiveViewport.Name, v => v);

    // get name of view to set active
    var gs = new GetString();
    gs.SetCommandPrompt("Name of view to set active");
    gs.AcceptNothing(true);
    gs.SetDefaultString(active_view_name);
    foreach (var view_name in non_active_views.Keys)
      gs.AddOption(view_name);
    var result = gs.Get();
    if (gs.CommandResult() != Result.Success)
      return gs.CommandResult();

    var selected_view_name =
      result == GetResult.Option ? gs.Option().EnglishName : gs.StringResult();

    if (selected_view_name != active_view_name)
      if (non_active_views.ContainsKey(selected_view_name))
        doc.Views.ActiveView = non_active_views[selected_view_name];
      else
        RhinoApp.WriteLine("\"{0}\" is not a view name", selected_view_name);

    return Rhino.Commands.Result.Success;
  }
}

Partial Friend Class Examples
  Public Shared Function SetActiveView(ByVal doc As RhinoDoc) As Result
	' view and view names
	Dim active_view_name = doc.Views.ActiveView.ActiveViewport.Name

	Dim non_active_views = doc.Views.Where(Function(v) v.ActiveViewport.Name <> active_view_name).ToDictionary(Function(v) v.ActiveViewport.Name, Function(v) v)

	' get name of view to set active
	Dim gs = New GetString()
	gs.SetCommandPrompt("Name of view to set active")
	gs.AcceptNothing(True)
	gs.SetDefaultString(active_view_name)
	For Each view_name In non_active_views.Keys
	  gs.AddOption(view_name)
	Next view_name
	Dim result = gs.Get()
	If gs.CommandResult() <> Result.Success Then
	  Return gs.CommandResult()
	End If

	Dim selected_view_name = If(result Is GetResult.Option, gs.Option().EnglishName, gs.StringResult())

	If selected_view_name IsNot active_view_name Then
	  If non_active_views.ContainsKey(selected_view_name) Then
		doc.Views.ActiveView = non_active_views(selected_view_name)
	  Else
		RhinoApp.WriteLine("""{0}"" is not a view name", selected_view_name)
	  End If
	End If

	Return Rhino.Commands.Result.Success
  End Function
End Class

from Rhino import *
from Rhino.Commands import *
from Rhino.Input import *
from Rhino.Input.Custom import *
from scriptcontext import doc

def RunCommand():
    # view and view names
    active_view_name = doc.Views.ActiveView.ActiveViewport.Name

    non_active_views = [(view.ActiveViewport.Name, view) for view in doc.Views if view.ActiveViewport.Name != active_view_name]

    # get name of view to set active
    gs = GetString()
    gs.SetCommandPrompt("Name of view to set active")
    gs.AcceptNothing(True)
    gs.SetDefaultString(active_view_name)
    for view_name, _ in non_active_views:
        gs.AddOption(view_name)
    result = gs.Get()
    if gs.CommandResult() != Result.Success:
        return gs.CommandResult()

    selected_view_name = "{0}".format(gs.StringResult())
    if gs.Option() != None:
        selected_view_name = gs.Option().EnglishName

    if selected_view_name != active_view_name:
        if selected_view_name in [seq[0] for seq in non_active_views]:
            doc.Views.ActiveView = [seq[1] for seq in non_active_views if seq[0] == selected_view_name][0]
        else:
            print "\"{0}\" is not a view name".format(selected_view_name)

    return Result.Success

if __name__ == "__main__":
    RunCommand()