Western boots can be worn with jeans or, surprise, a suit. The jeans can be western, or casual as long as the jeans are put together with a western shirt. If you wear western boots with a suit, you should either be wearing a western suit, or be wearing a western hat. Remember that jean shirts do not go with suits, western or otherwise. You might find that western boots do not go with most dresses but will go with all western dresses, and western skirt outfits.
Western blazers are fine with jeans and western boots.
You can add hat, and a big western buckle into the mix too but not too big of buckle though, as there are comfort issues at work. A denim shirt would be okay as long as it is a different colour than your jeans. With this outfit, ties are unnecessary. A bolo is fine, as are collar tips. A western shirt like this is naked without the combination of western jeans, boots, and hat.