Ok so let me preface this by saying, I don't really know you or live with you (), don't know your day to day routine and what your style is so I am going to give you some generic style advice with a bias towards what I wear/like. This type of advice is never meant to be taken word for word, but rather as a template into which you input your needs/desires and ideally come out a bit better than you went in.
It sounds like we dress in a similar fashion, probably most guys here who work in an office dress in a manner in which you described. So my first piece of advice is a navy sportcoat or two, a winter fall weight and something lighter, neither of them worsted wool. A navy coat is one of those things that you can wear 3-4 times a week, changing the shirt/tie/pants, and no one will think you are wearing the same thing. Another color that I suggest is brown for a sportcoat, something with texture and in a weight/fabric that you can wear 8 months of the year. Again, very versatile and changing the shirt/tie/pants, it won't look like you are wearing the same thing. I would further suggest getting more basic solid color or smal patterned jackets, different fabrics, until you have 4-5 or so. So there you have a stable of coats that you can wear with none being so in your face that everytime you wear it, everyone remembers the last time you wore it. After you have that, then you can go towards louder stuff.
Shirts/ties: You seem to like patterned shirts, which is fine. And you say that you wear a dress type shirt seemingly everyday. My preference for a shirt worn tieless with a sportcoat is a button down collar shirt, but I realize that is not to everyones taste. I would suggest not wearing spread collar shirts that have short to medium points tieless as they tend to disappear into a coat and also tend to make one's face look more rotund. With a tie, I wear both BD collars and regular collars. If you preference is to patterned shirts, your ties should lean to solids and micro prints. Solid ties sound boring but there are many great fabrics that provide good texture and accentuate the shirt/sportcoat. In terms of shirt colors, I would stay away from yellows, greens, purples and any solid dark colors or "odd" colors (taupe etc). Tie colors, I would stick with blues, greens, browns and red/rust.
Pants: You don't have to wear wool pants with sportcoats but I like their versatility. I would start with multiple solid grey pants (different shades/fabrics ), a brown or two, some textured stuff in browns/blues/greys (calvary twill, donegal, linen blends). In termsof khaki's, I would want to have 3-4 "dress" pairs, meaning nice fabric cotton or cotton blend pants that wear like wool pants. You can also get browns/greys in cotton/cotton blends. If it has a leather patch on the back or comes with the leg hemmed/finished, don't wear it with a sportcoat.
Shoes: I think sportcoats call for more "casual" dress shoes, meaning not super sleek, shiny shoes. NST's, brogues, boots, in suedes, dark leathers, grained etc. Sleek, formal shoes look good with suits (I don't like them but that is neither here nor there), but when you wear a pair of something very sleek with cotton pants and textured sportcoat, it looks silly to me. By the same token, don't wear cream/white suede shoes with rubber soles with grey wool pants, it just looks off.
So, all this stuff is subject to your intepretation and your style, you might not want or need multiple grey pants, or solid color ties but the basis behind this advice still stands, start off with versatile, classic basics and build out from there. If you have more patterned pants than you have solid, thats not good (assuming suit/sportcoat wardrobe). Same thing with sportcoats. Once you have the navy and grey suit, the mulitple white and blue shirts, the multiple boring ties, then you can branch out into the stuff that you think is fun. Its like anything else, build on the foundation and you'll find yourself with much more overall outfits as you'll be able to combine almost everything.
When I read on the forum someone just getting into dress shoes buying double monks or their first suit be a peak lapel slim suit or only buying unlined ties with hand rolled tips and throwing around all the buzzwords, I see someone heading into trouble. I don't know/think this because I'm some savant or incredibly knowledgeable about clothing and style but because I went through the same thing. I was the guy buying everything in sight that was an SF approved brand or trend, particularly if it was on sale. Never gave thought to how something I was buying works into my wardrobe or lifestyle. Eventually you look at your closet, full of clothes but you have a hard time putting together a good outfit. Then the purge starts.