As TSG said two of the options are to incorporate the transition, or hide it. It is hard to know which will work best in your space without knowing how big the crown will be and what style you have in mind, etc. Here are some examples of incorporating the window trim with the crown: [[(https://www.houzz.com/photos/traditional-bathroom-traditional-bathroom-new-york-phvw-vp~1034813) [Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Stamford Architects & Designers Sound Beach Partners LLC [[(https://www.houzz.com/photos/shingle-style-home-in-hanover-nh-victorian-bathroom-burlington-phvw-vp~106093) [Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Norwich Architects & Designers Smith & Vansant Architects PC [[(https://www.houzz.com/photos/chestnut-street-bathroom-traditional-bathroom-boston-phvw-vp~96002) [Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Boston Kitchen & Bath Designers Venegas and Company [[(https://www.houzz.com/photos/case-design-remodeling-inc-contemporary-bathroom-dc-metro-phvw-vp~87107) [Contemporary Bathroom[(https://www.houzz.com/photos/contemporary-bathroom-ideas-phbr1-bp~t_712~s_2103) by Bethesda Design-build Firms Case Design/Remodeling, Inc. [[(https://www.houzz.com/photos/weston-residence-traditional-bathroom-boston-phvw-vp~2583807) [Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Boston Architects & Designers Catalano Architects [[(https://www.houzz.com/photos/louisville-traditional-bathroom-atlanta-phvw-vp~116461) [Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Canton Furniture and Accessories The Furniture Guild Or transition with window treatments: [[(https://www.houzz.com/photos/fan-victorian-bathroom-los-angeles-phvw-vp~207997) [Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Los Angeles Interior Designers & Decorators Just Joh [[(https://www.houzz.com/photos/bathrooms-traditional-bathroom-phvw-vp~2678396) [Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Chester General Contractors ColeBuilt [[(https://www.houzz.com/photos/vacation-home-on-lake-michigan-traditional-bathroom-grand-rapids-phvw-vp~3286791) [Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Detroit Interior Designers & Decorators Urso Designs [[(https://www.houzz.com/photos/eclectic-bathroom-eclectic-bathroom-atlanta-phvw-vp~137747) [Eclectic Bathroom[(https://www.houzz.com/photos/eclectic-bathroom-ideas-phbr1-bp~t_712~s_2104) and this one, sort of in between: [[(https://www.houzz.com/photos/bluff-plantation-traditional-bathroom-atlanta-phvw-vp~58127) [Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Charleston Architects & Designers Frederick + Frederick Architects I hope this gives you some ideas!

Thanks for the replies so far. The window sill would be replaced if we go with the wider casing and may need to be replaced if we go with the narrow too. The padding out would put an inch piece of wood on all sides of the insides of the window (but not cover the glass), basically giving a wider surface onto which to attach the casing. There is just enough room for the 2 1/4 inch trim to fit and clear the corner of the crown. We mounted the crown so the top of the it would line up with the top of the casing. Here is another angle of the other kitchen. To me it looks like they took the wide casing all the way up to the ceiling and that the top of the crown covers a little corner of it. [Traditional Kitchen[(https://www.houzz.com/photos/traditional-kitchen-ideas-phbr1-bp~t_709~s_2107) by San Antonio Kitchen & Bath Designers BRADSHAW DESIGNS LLC

We find the height of base and crown that are most pleasing to the eye are the ones derived from classical proportions. For a 10' ceiling height, we would use 6 3/4" base and single-member cove or crown with a vertical projection of 4" Marianne Cusato's book "Getting Your House Right" is an excellent reference for moulding sizes--and lot's of other stuff, too.

5" for windows I think would be to wide. For base ok. Gee did I do something wrong since my window trim on my second floor with 9' ceilings is a 1 x 6 or 5.5" wide. Oh well. BTW: My base on my second floor is a 1 x 8 or 7.5" high. For the OP, I'd do the standard on the second floor and upgrade to the 5" just for the first floor base since money is an issue. Personally, I'd skip the crown for now and add it later if needed. As others have stated, you don't want your base to be the same width as the windows and door trim. The base should be larger than those.